You are presented with the question "What breathes by relaxing the lungs?" and the following answer choices: 
- mammals
 - tortoises
 - dogs
 - chickens
 - ducks
 - humans
 - crocodiles
 - animals

Now knowing that mammals breathe with the help of a diaphragm and belly breathing uses the diaphragm, which helps relax the lungs, choose the best answer.


 

 mammals        