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

Fact 2: Deltas and estuaries are important habitats.

Given the two facts above, answer the question "what is formed by deposition of sediment at the mouth of a river?" with the following options: 
- A solid geometric shape
 - clouds
 - h2o
 - important habitats
 - dams
 - patch reefs
 - swamp vegetation
 - at or near the margins


 

    important habitats     