Fact 1: Sound can be used for communication by animals.

Fact 2: Snarls and barks are the sounds they make.

Given the two facts above, answer the question "Some animals communicate through what?" with the following options: 
- chemical reaction
 - eating quietly
 - vibrating quickly
 - being silent
 - chemical changes
 - hormones
 - barks and snarls
 - chemical messengers


 

       barks and snarls  