Exfoliation/onion peeling in rocks is due to

Answer: Option C

Onion-skin weathering or exfoliation is the process of layers of the rock being peeled off like an onion.
When rock is exposed to physical erosion, these concentric layers peel off as concentric shells much like the layers of a peeled onion.
The main reasons behind the exfoliation in rocks are Temperature variation and different mineralogical compositions of rock.