Fact 1: Adelta is formed by deposition of sediment at the mouth of a river by water fanning out.

Fact 2: After sediments are deposited, they are gradually buried by more sediments.

Given the two facts above, answer the question "What can lead to the gradual burial of more sediments?" with the following options: 
- erosion
 - loose soil
 - an ocean
 - a wave
 - a delta
 - wind
 - a lake
 - flooding


 

     a delta    