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

Fact 2: When the river slows, it drops the sediment in a wide fan, a delta.

Given the two facts above, answer the question "Sediment is dropped at the mouth of a river by water when what happens?" with the following options: 
- Destroy bridges
 - erosion
 - global warming
 - rivers slow
 - flooding
 - contamination
 - massive damage
 - storms


 

    rivers slow     