You are presented with the question "what can break down rocks?" and the following answer choices: 
- Jellyfish
 - sea urchins
 - deltas
 - erosion
 - ice wedging
 - room temperature
 - clouds
 - cliffs

Now knowing that mechanical weathering is when rocks are broken down by mechanical means and ice wedging is the most important form of mechanical weathering, choose the best answer.


 

     ice wedging    