Which feature helps to maximize the volume of gases exchanged during internal expiration?
A.the level of oxygen in the blood
B.the level of carbon dioxide in the blood
C.the level of oxygen in the alveoli
D.the shape of the alveoli
E.the shape of the lungs
The answer is D or C because the alveoli are what give the lungs so much space, and if they are big, there is more gas exchange than if they are small.
