What is the main topographical reason for waterfalls in peninsular rivers?

Correct answer: Hard rocky surface and sudden change in slope

A waterfall forms where a river suddenly descends from a higher level to a lower level. In many parts of the Peninsular Plateau, layers of hard rock resist erosion while softer rock is worn away more quickly. Differences in rock resistance, together with a sudden break or steep change in the river’s slope, create a vertical drop. Continued erosion can make the drop more distinct over time.

Option C is correct because it identifies both important topographical conditions: a resistant rocky surface and an abrupt change in gradient. High sea waves do not normally create waterfalls in an inland river channel. Permanent glaciers are not the general cause of waterfalls in Peninsular India, and desert-sand deposition usually produces gentle landforms rather than a sharp drop. The supplied answer C is accurate.