You are presented with the question "What animal can help lakes to form?" and the following answer choices: 
- mussels
 - the trout
 - sea urchins
 - eukyarotes
 - the duck
 - The beaver
 - amphibians
 - the otter

Now knowing that damming a river can cause a lake to form and beavers build dams, choose the best answer.


 

      The beaver   