Final answer:
Increased oxygen diffusion from alveoli into blood occurs when there is a larger difference in partial pressures of oxygen in the alveoli and the blood.
Step-by-step explanation:
The situation that would result in increased oxygen diffusion from alveoli into the blood is when there is a larger difference in the partial pressures of oxygen in the alveoli and the blood. The partial pressure of oxygen in the alveoli is about 104 mm Hg, whereas the partial pressure of oxygenated blood in pulmonary veins is about 100 mm Hg.
This large difference creates a strong pressure gradient, allowing oxygen to rapidly cross the respiratory membrane from the alveoli into the blood.