Which major river flows through Meghalaya and forms the border with Bangladesh?

The correct answer is b) Barak.

The Barak River is a major river in northeastern India and Bangladesh. It is the largest tributary of the Brahmaputra River. The Barak River originates in the Manipur Hills in India and flows for about 500 kilometers (310 mi) before joining the Brahmaputra River in Bangladesh. The Barak River forms the border between India and Bangladesh for about 100 kilometers (62 mi).

The Barak River is an important source of water for irrigation and drinking water for millions of people in India and Bangladesh. The river is also a popular destination for fishing and boating.

The other options are incorrect because:

• The Brahmaputra River is a major river in northeastern India and Bangladesh. It is the longest river in India and the third longest river in Asia. The Brahmaputra River originates in the Himalayas in Tibet and flows for about 2,900 kilometers (1,800 mi) before joining the Ganges River in Bangladesh.
• The Subansiri River is a major river in northeastern India. It is a tributary of the Brahmaputra River. The Subansiri River originates in the Himalayas in Arunachal Pradesh and flows for about 700 kilometers (430 mi) before joining the Brahmaputra River in Assam.
• The Teesta River is a major river in northeastern India and Bangladesh. It is a tributary of the Brahmaputra River. The Teesta River originates in the Himalayas in Sikkim and flows for about 300 kilometers (190 mi) before joining the Brahmaputra River in Bangladesh.