Frost wedging is a form of weathering caused by water seeping into the cracks of rocks. This type of weathering is common in regions that have very cold winters. How does frost wedging take place?

A) This is a physical weathering process — when water freezes, it expands, pushing the rock apart slowly over a period of time.
B) This is a chemical weathering process — carbonic acid formed by the reaction of water and carbon dioxide breaks the bonds that hold the rock together.
C) This is a physical weathering process — when water freezes, the temperature of the rock is decreased, causing the outer layers of the rock to crumble off.
D) This is a chemical weathering process — water reacts with the chemicals in the rock by a process call hydrolysis and breaks the bonds that hold the rock together.
I am stumped on this. I think it is A. TIA!