Fact 1: Gills are used for breathing water by aquatic animals.

Fact 2: Fish are backboned aquatic animals.

Given the two facts above, answer the question "fish use gills for what" with the following options: 
- motility
 - breathing carbon dioxide
 - courtship
 - producing oxygen
 - biodiversity
 - breathing water
 - food and shelter
 - drinking water


 

      breathing water   