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

Fact 2: Animals breathe in oxygen and breathe out carbon dioxide.

Given the two facts above, answer the question "How do aquatic animals get oxygen?" with the following options: 
- photosynthesis
 - gills
 - rivers
 - blood
 - solutes
 - lungs
 - streams
 - carbon transfer


 

  gills       