Fact 1: Damming a river can cause a lake to form.

Fact 2: Beavers build dams.

Given the two facts above, answer the question "What animal can help lakes to form?" with the following options: 
- mussels
 - the trout
 - sea urchins
 - eukyarotes
 - the duck
 - The beaver
 - amphibians
 - the otter


 

      The beaver   