Tawa River is a tributary of which major west-flowing river?

Correct answer: Narmada

The governing concept is the tributary relationship within a drainage basin. The Tawa is an important tributary of the Narmada in central India and joins the Narmada system before the main river continues westward toward the Arabian Sea. Therefore option A is correct. Krishna is a major east-flowing peninsular river, Mahanadi also drains eastward into the Bay of Bengal, and the Ganga belongs to the northern Himalayan-plains drainage network. The phrase “major west-flowing river” narrows the answer, and the Tawa–Narmada pairing is a standard example of a tributary and its parent river.