Which statement best describes the function of the diaphragm in the body?

A. The diaphragm is a muscle that pulls air into the lungs and pushes air out as it moves.

B. The diaphragm is an organ that pulls air into the body and releases air later

C. The diaphragm is like a tree trunk with bronchi that work together to move air in and out.

D. The diaphragm has thin walls that uses capillaries to absorb oxygen and move it to the bloodstream