Gas Exchange Primarily Occurs in Which Portion of the Pulmonary

Gas exchange primarily occurs in which portion of the pulmonary anatomy?

A) Through the smooth muscle cells in the walls of the bronchi and bronchioles
B) Through the pulmonary arteries and veins
C) Through the cell membranes of the alveoli and the endothelium of the pulmonary capillaries
D) Through the parasympathetic fibers of the vagus nerve