You are presented with the question "What is pressed against when mammals breathe?" and the following answer choices: 
- objects that have mass
 - the skin
 - an organism's body
 - an object
 - layers of fat
 - matter vibrating
 - a cuticle
 - stomach muscles

Now knowing that mammals breathe with the help of a diaphragm and breathing Stomach muscles press against the resistance of the diaphragm, choose the best answer.


 

        stomach muscles 