Which feature is seen in exfoliation of rocks?

Correct answer: Removal of outer layers

The direct answer is A: removal or peeling of outer rock layers. Exfoliation is a type of physical weathering in which curved or sheet-like outer layers of a rock separate from the main mass. It may happen when pressure is released, when a rock repeatedly heats and cools, or when expansion and contraction create stress. Step by step: stress develops near the rock surface; cracks form roughly parallel to the surface; thin layers loosen and peel away; the exposed rock may become rounded. Option A is correct because it describes the defining feature of exfoliation. Option B is wrong because a long river valley is mainly a fluvial landform produced by river erosion, not the peeling of rock sheets. Option C is wrong because deposition of sea organisms may help form some limestone, but it is not exfoliation. Option D is wrong because cooling of magma forms igneous rock; it is not the later removal of outer layers by weathering. Exfoliation changes the shape of existing rock through physical forces and does not require chemical transformation. Memory cue: exfoliation is like a rock peeling in sheets, similar to layers coming off an onion.