Fact 1: Breathing is when a gill converts from oxygen in water into oxygen in blood.

Fact 2: Sharks breathe using gills.

Given the two facts above, answer the question "What do sharks use to convert oxygen?" with the following options: 
- gills
 - skin
 - blood
 - fins
 - Enzymes
 - mouth
 - tail
 - fibers


 

 gills        