Correct Answer: 

The correct answer is D: Brahmaputra.

Explanation of Options:

Option A: Ganga  
 • Incorrect. The Ganga River does not take a U-turn at Namcha Barwa.
 • The Ganga originates from the Gangotri Glacier in the Indian Himalayas and flows southeast across the plains of northern India.
 • It does not flow near the Namcha Barwa region, which is located in the eastern Himalayas.
 • The Ganga enters India from the north, not from the east.

Option B: Tista  
 • Incorrect. The Tista River does not take a U-turn at Namcha Barwa.
 • The Tista River originates in the eastern Himalayas and flows through the Indian states of Sikkim and West Bengal before entering Bangladesh.
 • It does not flow near the Namcha Barwa region.
 • The Tista is a tributary of the Brahmaputra but does not have a U-turn characteristic at Namcha Barwa.

Option C: Barak  
 • Incorrect. The Barak River does not take a U-turn at Namcha Barwa.
 • The Barak River originates in the Indian state of Manipur and flows into Bangladesh, where it is known as the Surma and Kushiyara rivers.
 • It does not flow near the Namcha Barwa region.
 • The Barak River is part of the Meghna River system, not the Brahmaputra.

Option D: Brahmaputra  
 • Correct. The Brahmaputra River takes a U-turn at Namcha Barwa.
 • The river originates in the Angsi Glacier in Tibet, where it is known as the Yarlung Tsangpo.
 • It takes a dramatic U-turn around the Namcha Barwa peak in the eastern Himalayas before entering India in the state of Arunachal Pradesh.
 • This U-turn is a significant geographical feature and marks the river's transition from Tibet into the Indian subcontinent.