The Deccan Plateau extends south of which river?

Correct answer: Narmada

The direct answer is B, the Narmada River. In school geography, the Deccan Plateau is the southern part of the Peninsular Plateau, lying broadly south of the Narmada valley. Step by step: the Narmada runs through a major rift valley; the region north of it includes the Central Highlands, while the large plateau extending southward is identified as the Deccan Plateau; therefore, Narmada is the boundary reference in this question. Option B is correct. Option A, Ganga, is wrong because the Ganga flows across the Northern Plains and is far north of the Deccan reference. Option C, Brahmaputra, is wrong because it lies mainly in the northeastern region and does not mark the northern limit of the Deccan Plateau. Option D, Indus, is wrong because it belongs mainly to the northwestern drainage system. The wording gives a broad geographical division, not a claim that every point has a sharp natural boundary. Memory cue: Narmada is the key north-side reference; Deccan lies to its south.