The correct answer is B. Brahmaputra River.
The Brahmaputra River is the longest river in India and the ninth longest river in the world. It is also the largest river in the Indian subcontinent, by both discharge and drainage basin area. The Brahmaputra River originates in the Himalayas in Tibet, and flows through India and Bangladesh before emptying into the Bay of Bengal. The river is a major source of water for irrigation, drinking water, and hydroelectric power for millions of people in the region.
The Barak River is the second longest river in Assam, after the Brahmaputra. It originates in the Manipur Hills in India, and flows through the states of Manipur, Mizoram, and Assam before emptying into the Bay of Bengal. The Barak River is a major source of water for irrigation, drinking water, and hydroelectric power for millions of people in the region.
The Disang River is a tributary of the Brahmaputra River. It originates in the Himalayas in Tibet, and flows through the states of Arunachal Pradesh and Assam before joining the Brahmaputra River. The Disang River is a major source of water for irrigation, drinking water, and hydroelectric power for millions of people in the region.
None of these is not the correct answer.