If when ice causes rocks to crack by expanding in openings, this is known as mechanical weathering, then when ice causes rocks to crack by expanding in openings, what is this called?

Answer choices:
- In the winter
 - smoking
 - icing
 - fissures of hot, acidic water
 - mechanical weathering
 - graptolites
 - Inches or fractions of inches.
 - rocking

 

     mechanical weathering     