3. Why does oxygen diffuse into the blood from an alveolus in the lungs?




A The oxygen concentration in the alveolus is greater than the carbon dioxide concentration in
the blood.


B The oxygen concentration in the alveolus is greater than in the blood.

C The oxygen concentration in the blood is greater than in the alveolus.

D The oxygen concentration in the blood is greater than the carbon dioxide concentration in the alveolus.