Examine the Figure Shown

Examine the figure shown. During breathing in humans, ________.

A) the diaphragm moves downward and the rib muscles contract, increasing the size of the chest cavity and decreasing the air pressure within the chest cavity
B) the nasal cavities expand and the diaphragm relaxes
C) the diaphragm and rib muscles contract, decreasing the size of the chest cavity and increasing the pressure within the chest cavity
D) the diaphragm moves downward and the rib muscles relax, increasing the size of the chest cavity and decreasing the air pressure within the chest cavity