Answer:
C. Water freezes and thaws inside rock cracks, causing them to widen and then split.
Step-by-step explanation:
When water gets in the crack at the bottom and freezes, frost wedging occurs.
Frost wedging happens when water gets in crack, freezes, and expands. This process breaks rocks apart. When this process is repeated, cracks in rocks get bigger and bigger (see diagram below) and may fracture, or break, the rock.