Frost Wedging Is Most Effective __ $\degree$ C at Night and Above 0

Multiple Choice

Frost wedging is most effective __.

A) in areas with many days of freezing and thawing
B) in the winter when the rock is frozen solid for months on end
C) in the spring and fall in very dry desert areas where temperatures dip down below 0 $\degree$ C at night and above 0 $\degree$ C during the day
D) in the summer when abundant rainfall percolates through the cracks to freeze in contact with the very cold rock found deep below the surface