How does the movement of muscles attached to the ribcage and diaphragm initiate expiration? (3 points)

a
The muscles relax, which which flattens the diaphragm and increases the volume of the chest cavity.
b
The muscles relax, which pulls the ribcage downward and decreases the volume of the chest cavity.
c
The lungs contract and push the air from the lungs.
d
The lungs relax and pull the air into the lungs.