SEBA Elective Geography Chapter 4 Important Extra Questions | Assam Eduverse
SEBA Elective Geography Chapter 4 Important Extra Questions are prepared to help students understand the major concepts of Regional Geography of U.S.A. in a clear and exam-oriented manner. SEBA Elective Geography Chapter 4 Important Extra Questions focus on important topics such as physical regions, climate, natural resources, agriculture, industries, and population distribution of the United States of America.
SEBA Elective Geography Chapter 4 Important Extra Questions strictly follow the latest SEBA (ASSEB) syllabus and are updated for the academic session 2026–27. Each of the SEBA Elective Geography Chapter 4 Important Extra Questions is selected after analysing previous year examination trends to ensure relevance and scoring value.
Students searching for SEBA Advanced Geography Important Questions or ASSEB Class 10 Advanced Geography Extra Questions will find SEBA Elective Geography Chapter 4 Important Extra Questions extremely useful for developing regional understanding and focused revision.
SEBA Elective Geography Chapter 4 Regional Geography of U.S.A. Important Questions | Previous Year Questions
Table of Contents
A. Previous Year Very Short Type Questions (MCQs – 1 Mark)
Q1. The total area of the U.S.A. is — [HSLC 2010]
(i) 7.5 million sq. km
(ii) 9.5 million sq. km
(iii) 10.5 million sq. km
(iv) 8.5 million sq. km
Answer: (ii) 9.5 million sq. km
Q2. The total number of states of the U.S.A. is — [HSLC 2011]
(i) 55
(ii) 35
(iii) 45
(iv) 50
Answer: (iv) 50
Q3. Which of the following states of the U.S.A. is located in its northern part? [HSLC 2011]
(i) Utah
(ii) Texas
(iii) Montana
(iv) Virginia
Answer: (iii) Montana
Q4. Which of the following states of the U.S.A. is located in its Central Plain region? [HSLC 2015]
(i) Alabama
(ii) Oregon
(iii) Virginia
(iv) Utah
Answer: (i) Alabama
Q5. The mainland of the U.S.A. lies between the latitudes — [HSLC 2016]
(i) 45°N – 59°N
(ii) 50°N – 63°N
(iii) 25°N – 43°N
(iv) 35°N – 59°N
Answer: (iii) 25°N – 43°N
Q6. Which one of the following rivers of the U.S.A. flows into the Pacific Ocean? [HSLC 2018]
(i) Missouri
(ii) Snake
(iii) Ohio
(iv) Tennessee
Answer: (ii) Snake
Q7. In which of the following regions is located the Great Lake Region of the U.S.A.? [HSLC 2017]
(i) Appalachian Highlands Region
(ii) The Central Plain Region
(iii) Rocky Mountain Region
(iv) California Coastal Region
Answer: (ii) The Central Plain Region
Q8. The densely populated region of the U.S.A. is located in — [HSLC 2019]
(i) Eastern part of the U.S.A.
(ii) Western part of the U.S.A.
(iii) Central part of the U.S.A.
(iv) Southern part of the U.S.A.
Answer: (i) Eastern part of the U.S.A.
Q9. The Erie of the United States of America is a — [HSLC 2020]
(i) Plateau
(ii) Mountain
(iii) Lake
(iv) Waterfall
Answer: (iii) Lake
Extra Short Type Questions (MCQs – 1 Mark)
Q1. The U.S.A. is located in which hemisphere?
(i) Southern Hemisphere
(ii) Eastern Hemisphere
(iii) Northern Hemisphere
(iv) Southern and Eastern Hemisphere
Answer: (iii) Northern Hemisphere
Q2. The mainland of the U.S.A. lies between —
(i) 10°N–30°N
(ii) 25°N–43°N
(iii) 35°N–60°N
(iv) 45°N–70°N
Answer: (ii) 25°N–43°N
Q3. The total number of states in the U.S.A. is —
(i) 48
(ii) 49
(iii) 50
(iv) 51
Answer: (iii) 50
Q4. Which ocean lies to the east of the U.S.A.?
(i) Pacific Ocean
(ii) Indian Ocean
(iii) Atlantic Ocean
(iv) Arctic Ocean
Answer: (iii) Atlantic Ocean
Q5. Which ocean lies to the west of the U.S.A.?
(i) Atlantic Ocean
(ii) Indian Ocean
(iii) Arctic Ocean
(iv) Pacific Ocean
Answer: (iv) Pacific Ocean
Q6. The Appalachian Highlands are located in the —
(i) Western part
(ii) Central part
(iii) Eastern part
(iv) Southern part
Answer: (iii) Eastern part
Q7. Which mountain range lies in the western part of the U.S.A.?
(i) Appalachian Mountains
(ii) Rocky Mountains
(iii) Aravalli Mountains
(iv) Andes Mountains
Answer: (ii) Rocky Mountains
Q8. The Central Plain of the U.S.A. is mainly suitable for —
(i) Mining
(ii) Fishing
(iii) Agriculture
(iv) Tourism
Answer: (iii) Agriculture
Q9. Which is the longest river of the U.S.A.?
(i) Missouri
(ii) Mississippi
(iii) Colorado
(iv) Columbia
Answer: (ii) Mississippi
Q10. Which river system is known as the longest river system of the U.S.A.?
(i) Mississippi–Missouri
(ii) Colorado River system
(iii) Columbia River system
(iv) Ohio River system
Answer: (i) Mississippi–Missouri
Q11. The Mississippi River flows into the —
(i) Atlantic Ocean
(ii) Pacific Ocean
(iii) Gulf of Mexico
(iv) Arctic Ocean
Answer: (iii) Gulf of Mexico
Q12. Which river of the U.S.A. flows into the Pacific Ocean?
(i) Ohio
(ii) Tennessee
(iii) Snake
(iv) Missouri
Answer: (iii) Snake
Q13. The Great Lakes are located in the —
(i) Western Highlands
(ii) Central Plain Region
(iii) Appalachian Highlands
(iv) Southern Coastal Plain
Answer: (ii) Central Plain Region
Q14. Which of the following is a Great Lake?
(i) Lake Victoria
(ii) Lake Erie
(iii) Lake Baikal
(iv) Lake Titicaca
Answer: (ii) Lake Erie
Q15. The climate of the U.S.A. is mainly —
(i) Tropical
(ii) Desert
(iii) Temperate
(iv) Polar
Answer: (iii) Temperate
Q16. Which region of the U.S.A. is most densely populated?
(i) Eastern region
(ii) Western region
(iii) Central region
(iv) Southern region
Answer: (i) Eastern region
Q17. The Prairie grasslands are found in the —
(i) Eastern Highlands
(ii) Central Plains
(iii) Western Highlands
(iv) Southern Plains
Answer: (ii) Central Plains
Q18. Which agricultural belt is famous for wheat cultivation?
(i) Cotton Belt
(ii) Corn Belt
(iii) Wheat Belt
(iv) Rice Belt
Answer: (iii) Wheat Belt
Q19. Which agricultural belt is famous for maize cultivation?
(i) Wheat Belt
(ii) Cotton Belt
(iii) Corn Belt
(iv) Rice Belt
Answer: (iii) Corn Belt
Q20. The Cotton Belt is mainly located in the —
(i) Northern U.S.A.
(ii) Western U.S.A.
(iii) Southern U.S.A.
(iv) Central U.S.A.
Answer: (iii) Southern U.S.A.
Q21. Which is the most industrially developed country of the world?
(i) Japan
(ii) China
(iii) U.S.A.
(iv) Germany
Answer: (iii) U.S.A.
Q22. Which industrial region is the oldest in the U.S.A.?
(i) Pacific Coast Industrial Region
(ii) Southern Industrial Region
(iii) North Eastern Industrial Region
(iv) Central Industrial Region
Answer: (iii) North Eastern Industrial Region
Q23. The Pacific Coast Industrial Region is famous for —
(i) Cotton textile
(ii) Heavy industries
(iii) Ship building and aircraft industry
(iv) Jute industry
Answer: (iii) Ship building and aircraft industry
Q24. Which mineral resource is abundantly found in the U.S.A.?
(i) Coal
(ii) Diamond
(iii) Gold only
(iv) Uranium only
Answer: (i) Coal
Q25. Which factor mainly helped industrial development of the U.S.A.?
(i) Scarcity of resources
(ii) Lack of transport
(iii) Availability of resources
(iv) Poor market
Answer: (iii) Availability of resources
Q26. The Southern Coastal Plain region is suitable for —
(i) Wheat cultivation
(ii) Rice and sugarcane cultivation
(iii) Tea cultivation
(iv) Coffee cultivation
Answer: (ii) Rice and sugarcane cultivation
Q27. Which region of the U.S.A. is rich in iron and coal?
(i) Appalachian Highlands
(ii) Central Plains
(iii) Western Highlands
(iv) Coastal Plains
Answer: (i) Appalachian Highlands
Q28. The standard of living in the U.S.A. is —
(i) Low
(ii) Moderate
(iii) Very high
(iv) Very poor
Answer: (iii) Very high
Q29. Which sector plays a major role in the economy of the U.S.A.?
(i) Agriculture
(ii) Industry
(iii) Services
(iv) All of these
Answer: (iv) All of these
Q30. The U.S.A. is an economically —
(i) Backward country
(ii) Developing country
(iii) Developed country
(iv) Underdeveloped country
Answer: (iii) Developed country
B. Previous Year Very Short Type Questions (1 Mark)
Q1. Name an important tributary of the Mississippi River. [HSLC 2010]
Answer: Missouri River
Q2. Name the ocean located on the west of the U.S.A. [HSLC 2011]
Answer: Pacific Ocean
Q3. State the name of the grassland found in Brazil. [HSLC 2012]
Answer: Campos
Q4. How many states constitute the U.S.A.? [HSLC 2013]
Answer: 50
Q5. Which part of the U.S.A. is densely populated? [HSLC 2014]
Answer: Eastern part of the U.S.A.
Q6. Write the name of one agricultural belt of the U.S.A. [HSLC 2015, 2017]
Answer: Cotton Belt
(also acceptable: Wheat Belt / Corn Belt)
Q7. In which part of the U.S.A. are the Appalachian Highlands located? [HSLC 2015]
Answer: Eastern part of the U.S.A.
Q8. What is the land area of the U.S.A.? [HSLC 2018, 2020]
Answer: About 9.5 million sq. km
Q9. Mention one west-flowing river of the Rocky Mountain region of the U.S.A. [HSLC 2019]
Answer: Columbia River
(also acceptable: Colorado River)
Q10. Name four lakes of the Great Lake region of the U.S.A. [HSLC 2013]
Answer: The four lakes of the Great Lake region of the U.S.A. are
- Lake Superior
- Lake Michigan
- Lake Huron
- Lake Erie
Q11. Name two rivers of the U.S.A. [HSLC 2015]
Answer: Two rivers of the U.S.A are Mississippi and
Missouri
Q12. Write the names of the Great Lakes of the U.S.A. [HSLC 2016]
Answer: Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario
Q13. Mention the name of two states of the U.S.A. located in its southern part. [HSLC 2018]
Answer:Texas and Alabama
Q14. Name two states of the Appalachian Highland region of the U.S.A. [HSLC 2019]
Answer:
Virginia
Pennsylvania
Q15. Name any two rivers of North America. [HSLC 2020]
Answer: The two rivers of North America are-
- Mississippi
- St. Lawrence
Extra Very Short Type Questions (1 Mark)
Q1. In which hemisphere is the U.S.A. located?
Answer: Northern Hemisphere
Q2. Name the ocean lying to the east of the U.S.A.
Answer: Atlantic Ocean
Q3. Name the ocean lying to the west of the U.S.A.
Answer: Pacific Ocean
Q4. How many states are there in the U.S.A.?
Answer: 50
Q5. What is the approximate area of the U.S.A.?
Answer: About 9.5 million sq. km
Q6. Name the longest river of the U.S.A.
Answer: Mississippi River
Q7. Name one important tributary of the Mississippi River.
Answer: Missouri River
Q8. Into which water body does the Mississippi River flow?
Answer: Gulf of Mexico
Q9. Name one river flowing westward from the Rocky Mountains.
Answer: Colorado River
Q10. Name any one Great Lake of the U.S.A.
Answer: Lake Erie
(also acceptable: Superior / Michigan / Huron / Ontario)
Q11. Which region of the U.S.A. is known as the Central Plain?
Answer: Middle part of the U.S.A.
Q12. Name the grassland found in the Central Plains of the U.S.A.
Answer: Prairie
Q13. Which mountain range is located in the eastern part of the U.S.A.?
Answer: Appalachian Mountains
Q14. Which mountain range is located in the western part of the U.S.A.?
Answer: Rocky Mountains
Q15. Name one agricultural belt of the U.S.A.
Answer: Wheat Belt
(also acceptable: Corn Belt / Cotton Belt)
Q16. Which agricultural belt is famous for cotton cultivation?
Answer: Cotton Belt
Q17. Which agricultural belt is famous for maize cultivation?
Answer: Corn Belt
Q18. Which agricultural belt is famous for wheat cultivation?
Answer: Wheat Belt
Q19. Which part of the U.S.A. is most densely populated?
Answer: Eastern part
Q20. Name one state of the southern part of the U.S.A.
Answer: Texas
(also acceptable: Alabama / Louisiana)
Q21. Name one state of the northern part of the U.S.A.
Answer: Montana
Q22. Which region of the U.S.A. is rich in coal and iron?
Answer: Appalachian Highland Region
Q23. Name the oldest industrial region of the U.S.A.
Answer: North-Eastern Industrial Region
Q24. Name one industrial region of the U.S.A.
Answer: Pacific Coast Industrial Region
Q25. Which industrial region is the youngest in the U.S.A.?
Answer: Pacific Coast Industrial Region
Q26. Name one important factor for industrial development of the U.S.A.
Answer: Availability of natural resources
Q27. Which climate mainly prevails in the U.S.A.?
Answer: Temperate climate
Q28. Name one mineral resource found in abundance in the U.S.A.
Answer: Coal
Q29. What is the standard of living in the U.S.A.?
Answer: Very high
Q30. The U.S.A. is an economically…………….. country.
Answer: Developed country
C. Previous Year Short Answer Type Questions (2–3 Marks)
Q1. Name two physiographic regions of the U.S.A. [HSLC 2010]
Answer: Two physiographic regions of the U.S.A. are: Appalachian Highland, Central Plain
Q2. Mention two agricultural belts of the U.S.A. [HSLC 2010]
Answer: Two important agricultural belts of the U.S.A. are: Wheat Belt, Corn Belt
Q3. Name two major industrial regions of the U.S.A. [HSLC 2011]
Answer: Two major industrial regions of the U.S.A. are: North-Eastern Industrial Region, Pacific Coast Industrial Region
Q4. Name two mountains of the U.S.A. [HSLC 2013, 2017]
Answer: Two mountain ranges of the U.S.A. are: Rocky Mountains, Appalachian Mountains
Q5. Name two Great Lakes of the U.S.A. [HSLC 2014]
Answer: Two Great Lakes of the U.S.A. are: Lake Superior, Lake Erie
Q6. Name two rivers of the U.S.A. [HSLC 2015]
Answer: Two important rivers of the U.S.A. are: Mississippi River, Missouri River
Q7. Write the names of the Great Lakes of the U.S.A. [HSLC 2016]
Answer: The five Great Lakes of the U.S.A. are: Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario.
Q8. Mention the names of two states of the U.S.A. located in its southern part. [HSLC 2018]
Answer: Two southern states of the U.S.A. are: Texas, Alabama
Q9. Write the names of three major east-flowing rivers of South America. [HSLC 2018]
Answer: Three major east-flowing rivers of South America are: Amazon, Orinoco, Paraná
Q10. Name two states of the Appalachian Highland region of the U.S.A. [HSLC 2019]
Answer: Two states of the Appalachian Highland region are: Pennsylvania, Virginia
Q11. Briefly discuss the role of agriculture in the economy of the U.S.A. [HSLC 2019]
Answer: Agriculture plays an important role in the economy of the U.S.A. The country practices large-scale and mechanised farming. It produces surplus food grains like wheat, maize and cotton, which support agro-based industries and export trade.
Q12. Write briefly on the Pacific Coast Industrial Region of the U.S.A. [HSLC 2019]
Answer: The Pacific Coast Industrial Region is located along the western coast of the U.S.A. It is the youngest industrial region of the country. Ship-building, aircraft industry, petroleum refining and electronics industries are important here.
Q13. Name any two rivers of North America. [HSLC 2020]
Answer: Two rivers of North America are: Mississippi River, St. Lawrence River
Q14. Write about the mineral resources of the U.S.A. [HSLC 2020]
Answer: The U.S.A. is rich in mineral resources. Coal, iron ore, petroleum and natural gas are found in large quantities. These mineral resources have greatly helped the industrial development of the country.
Q15. Write a brief note on the climate of the continent of South America. [HSLC 2020]
Answer: South America experiences varied climates due to its large size. Equatorial climate is found near the Amazon Basin, tropical climate in the central parts, and temperate climate in the southern regions. Rainfall is heavy in the equatorial region.
Extra Short Answer Type Questions (2–3 Marks)
Q1. Mention the latitudinal extent of the mainland of the U.S.A.
Answer: The mainland of the U.S.A. extends approximately from 25° north latitude to 43° north latitude, placing it mainly in the temperate zone.
Q2. State two reasons for dense population in the eastern part of the U.S.A.
Answer: The eastern part of the U.S.A. is densely populated because it has a favourable climate and was the first region to develop industries and transport facilities.
Q3. Name two west-flowing rivers of the U.S.A.
Answer: Two important west-flowing rivers of the U.S.A. are the Colorado River and the Columbia River, which originate in the Rocky Mountains and flow into the Pacific Ocean.
Q4. Describe two physical features of the Central Plain of the U.S.A.
Answer: The Central Plain of the U.S.A. is a vast low-lying flat land with fertile soil, making it highly suitable for large-scale agricultural activities.
Q5. Write two characteristics of the Appalachian Highlands.
Answer: The Appalachian Highlands are old fold mountains and are rich in mineral resources like coal and iron, which helped early industrial growth in the region.
Q6. Name two important tributaries of the Mississippi River.
Answer: The Missouri River and the Ohio River are two major tributaries of the Mississippi River and together form an important river system of the U.S.A.
Q7. Mention two features of the Prairie grasslands.
Answer: The Prairie grasslands are treeless grasslands with fertile soil and are well suited for mechanised farming, especially wheat and maize cultivation.
Q8. Name two crops grown in the Wheat Belt of the U.S.A.
Answer: The Wheat Belt mainly produces wheat, and along with it crops like barley are also grown in this region.
Q9. Name two crops grown in the Corn Belt of the U.S.A.
Answer: The Corn Belt is famous for the cultivation of maize and also produces soybean on a large scale.
Q10. Write two reasons for the development of agriculture in the U.S.A.
Answer: Agriculture in the U.S.A. developed due to the availability of fertile plains and the extensive use of modern machines and scientific farming methods.
Q11. Name two important industrial cities of the North-Eastern Industrial Region.
Answer: New York and Chicago are two important industrial cities of the North-Eastern Industrial Region of the U.S.A.
Q12. Mention two industries of the North-Eastern Industrial Region.
Answer: The North-Eastern Industrial Region is well known for iron and steel industries and engineering industries.
Q13. Write two features of the Southern Industrial Region of the U.S.A.
Answer: The Southern Industrial Region developed mainly due to the availability of agricultural raw materials and resources like petroleum and natural gas.
Q14. Name two industries found in the Southern Industrial Region.
Answer: Important industries of the Southern Industrial Region include the cotton textile industry and chemical industry.
Q15. Mention two characteristics of the Pacific Coast Industrial Region.
Answer: The Pacific Coast Industrial Region is the youngest industrial region of the U.S.A. and largely depends on hydroelectric power and petroleum resources.
Q16. Name two important industrial cities of the Pacific Coast Industrial Region.
Answer: Los Angeles and San Francisco are two major industrial cities of the Pacific Coast Industrial Region.
Q17. Write two reasons for the industrial development of the U.S.A.
Answer: The U.S.A. developed industries due to its abundant natural resources and a well-developed transport and communication system.
Q18. Name two mineral fuels found in the U.S.A.
Answer: Two important mineral fuels found in the U.S.A. are coal and petroleum, which play a vital role in industrial growth.
Q19. Mention two metallic minerals found in the U.S.A.
Answer: The U.S.A. has deposits of metallic minerals like iron ore and copper, which are important for heavy industries.
Q20. Write two uses of coal in the U.S.A.
Answer: Coal is mainly used for generating electricity and in the iron and steel industry of the U.S.A.
Q21. Name two rivers used for inland water transport in the U.S.A.
Answer: The Mississippi River and the Ohio River are widely used for inland water transport in the U.S.A.
Q22. Mention two advantages of the Mississippi–Missouri river system.
Answer: The Mississippi–Missouri river system provides a long navigable route and greatly helps in trade, agriculture and transportation.
Q23. Write two features of the climate of the U.S.A.
Answer: The climate of the U.S.A. is mainly temperate in nature and shows clear seasonal variations.
Q24. Mention two reasons for the high standard of living in the U.S.A.
Answer: The high standard of living in the U.S.A. is due to high industrial development and high per capita income.
Q25. Name two factors responsible for the economic development of the U.S.A.
Answer: Economic development in the U.S.A. is the result of advanced technology and a skilled and educated workforce.
Q26. Write two characteristics of mechanised farming in the U.S.A.
Answer: Mechanised farming in the U.S.A. involves the use of modern machines and large-sized farms, which increase productivity.
Q27. Mention two advantages of large-scale farming in the U.S.A.
Answer: Large-scale farming helps in producing crops in large quantities and reducing the cost of production.
Q28. Name two coastal plains of the U.S.A.
Answer: The Atlantic Coastal Plain and the Gulf Coastal Plain are two important coastal plains of the U.S.A.
Q29. Write two economic activities of the Coastal Plains of the U.S.A.
Answer: The Coastal Plains of the U.S.A. support agriculture and fishing activities, contributing to the economy.
Q30. Mention two reasons why the U.S.A. is a developed country.
Answer: The U.S.A. is considered a developed country due to its high level of industrialisation and advanced transport and communication systems.
SEBA Elective Geography Chapter 4 Important Extra Questions play an important role in strengthening exam preparation when practised regularly. SEBA Elective Geography Chapter 4 Important Extra Questions help students revise answers efficiently and improve understanding of Regional Geography of U.S.A. Repeated practice of SEBA Elective Geography Chapter 4 Important Extra Questions enhances answer-writing skills and confidence.
By focusing on SEBA Elective Geography Chapter 4 Important Extra Questions, students can identify high-scoring areas and avoid unnecessary topics. SEBA Elective Geography Chapter 4 Important Extra Questions also support preparation alongside HSLC Advanced Geography Chapter-wise Important Questions, ensuring balanced syllabus coverage.
Students preparing with SEBA Elective Geography Chapter 4 Important Extra Questions gain accuracy in answering regional geography questions. In conclusion, SEBA Elective Geography Chapter 4 Important Extra Questions act as a reliable study tool that helps students enter the examination hall confident, well-prepared, and ready to score high marks using Elective Geography Chapter 4 Regional Geography of U.S.A. Important Questions.
Frequently Asked Questions (FAQ)
1. Why is Chapter 4 Regional Geography of U.S.A. important?
This chapter is important for understanding the physical and economic regions of the U.S.A. and carries good weightage in Elective Geography.
2. Are these important extra questions based on the SEBA syllabus?
Yes, all SEBA Elective Geography Chapter 4 Important Extra Questions are prepared as per the latest SEBA (ASSEB) syllabus for 2026–27.
3. Do these questions include previous year examination questions?
Yes, many questions from Regional Geography of U.S.A. are framed based on previous year examination trends.
4. Are these questions exam-oriented?
Yes, these questions are fully exam-oriented and suitable for Elective Geography preparation.
5. Are these questions useful for last-minute revision?
Yes, these Regional Geography of U.S.A. extra questions are ideal for quick revision.
6. Is this content suitable for ASSEB students?
Yes, SEBA and ASSEB are the same board, so the content applies to all students.
7. Why should I study Elective Geography from Assam EduVerse?
Assam EduVerse provides syllabus-based, exam-focused, and reliable SEBA Elective Geography study resources.
🎓 About Assam Eduverse
Assam Eduverse is the best educational platform in Assam, offering SEBA, AHSEC (ASSEB), SCERT, CBSE, and Assam Board Solutions along with study materials, notes, and exam preparation guides to help students learn smarter and score higher.
Our expert-prepared answers and MCQs follow the latest Assam Board Syllabus and NCERT Syllabus. We make learning simple, accessible, and effective for all students preparing for board or competitive exams.📘 Visit Assam Eduverse for free Assam Board Solutions, notes, and Study Materials prepared by experts.