Oxygen Diffusion from the Alveolus to the Pulmonary Capillary Occurs

Multiple Choice

Oxygen diffusion from the alveolus to the pulmonary capillary occurs because

A) alveolar PO₂ is greater than capillary PO₂.
B) oxygen diffuses faster than carbon dioxide.
C) alveolar PCO₂ is greater than capillary PCO₂.
D) alveolar PO₂ is less than capillary PCO₂.
E) carbon dioxide diffuses faster than oxygen.