The Narmada and the Tapi are unusual among peninsular rivers because they

The correct answer is B. Both rivers flow westward along faulted troughs, or rift valleys, that lie between the Vindhya and the Satpura ranges, and both empty into the Arabian Sea through estuaries instead of deltas. Most other large peninsular rivers, such as the Godavari, the Krishna and the Kaveri, flow eastward down the general slope of the Deccan.

Option A is wrong because both are peninsular rivers: the Narmada rises at Amarkantak and the Tapi in the Betul district of Madhya Pradesh, far from the Himalaya. Option C is wrong because a river flowing into the Arabian Sea through a rift cannot build an eastern delta; in fact the swift flow and the narrow trough prevent either river from building a delta at all. Option D is wrong because both are perennial rivers of considerable size, the Narmada being the largest west-flowing river of the peninsula.