You are presented with the question "What is caused by cycles of water freezing and thawing?" and the following answer choices: 
- heat is produced
 - a tree falling
 - peachleaf willow
 - Plant growth is reduced
 - root growth
 - mechanical weathering
 - Condensation
 - fissures of hot, acidic water

Now knowing that cycles of freezing and thawing water cause ice wedging and ice wedging is the most important form of mechanical weathering, choose the best answer.


 

      mechanical weathering   