Fact 1: Ice wedging is when ice causes rocks to crack by expanding in openings.

Fact 2: Ice wedging is extremely effective in a moist but cold climate.

Given the two facts above, answer the question "what causes rocks to crack from ice expanding into openings?" with the following options: 
- evaporation
 - In the winter
 - tropical climates
 - heat energy
 - hot, dry climates
 - moist, cold climates
 - colder weather
 - Inches or fractions of inches.


 

      moist, cold climates   