Which of the following is a type of physical weathering?

Exfoliation is correctly identified as a type of physical weathering because it involves the mechanical breakdown of rocks without changing their chemical composition. This process occurs when outer layers of rock expand and contract due to temperature changes, often leading to the peeling or flaking off of these outer layers. Physical weathering encompasses various processes that result in the fragmentation of rocks, and exfoliation is a prime example as it emphasizes physical changes rather than chemical alterations.

Chemical weathering, while an important process in the breakdown of rocks, involves chemical reactions that change the mineral composition of the rocks, which is why it doesn't fit into the category of physical weathering. Erosion refers to the movement of weathered material rather than the breakdown of the rocks themselves, and acid rain involves a chemical reaction with rainwater that can lead to chemical weathering processes, further distinguishing it from physical weathering. Thus, exfoliation stands out clearly as a physical weathering process.