Why can outer layers be more affected in thermal weathering?

Correct answer: Because they remain in direct contact with heat

Correct answer: A, because outer layers are in direct contact with changing heat conditions. Rock surfaces receive heating and cooling before the deeper interior. During strong heating, the outer part expands; during cooling, it contracts. Repeated expansion and contraction create stress, especially near the surface. Over time, cracks may develop parallel to the surface and thin sheets can peel or break away. This is thermal or exfoliation weathering, a physical process because the rock is broken without necessarily changing its minerals chemically. B is wrong because outer rock layers are not always underwater, and submergence is not the basic cause here. C is wrong because thermal weathering does not require rocks to become magnetic. D is wrong because fossil formation is a biological and sedimentary process, not the explanation for temperature stress. Memory cue: surface heats first, expands first, cools first, and contracts first.