You are presented with the question "what causes weathering over long periods of time?" and the following answer choices: 
- rocks
 - coastlines
 - respiration
 - alluvial
 - erosion
 - loose soil
 - rainfall
 - perspiration

Now knowing that rocks interacting with wind over long periods of time causes weathering and erosion happens when water or wind wears away bits of rock, choose the best answer.


 

     erosion    