The correct option is D more than that in the blood
At the respiratory membrane, where the alveolar and capillary walls are in extreme close proximity, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting from it.
Partial pressure of a gas is the pressure exerted by an individual gas in a mixture of gases. A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower.
The partial pressure of oxygen in the alveoli of the lung is more than that in the blood, as the blood is deoxygenated. This difference in pressure helps in the diffusion of oxygen from the alveoli into the blood.