What causes oxygen to diffuse into the blood from an alveolus in the lungs?
- AThe oxygen concentration in the alveolus is greater than the carbon dioxide concentration in the blood.
- BThe oxygen concentration in the alveolus is greater than in the blood.
- CThe oxygen concentration in the blood is greater than in the alveolus.
- DThe oxygen concentration in the blood is greater than the carbon dioxide concentration in the alveolus.