You are presented with the question "A delta is formed by " and the following answer choices: 
- erosion
 - motion
 - plate shifts
 - flooding
 - loose soil
 - Earthworms
 - compression
 - gravity

Now knowing that adelta is formed by deposition of sediment at the mouth of a river by water fanning out and erosion is responsible for wearing down exposed places and depositing sediment in level places, choose the best answer.


 

 erosion        