Answer:
Diagram (A).
Step-by-step explanation:
Oxygen can move by the process of the diffusion. Diffusion is the process of movement of solute particles towards the region of lower concentration from the region of higher concentration .
As shown in the diagram (A) The oxygen amount is low as compared outside the cell. The oxygen molecules will move from outside of the cells to the inside of the cell by the process of diffusion. The large difference in the concentration gradient between inside and outside of the cells allow the diffusion faster.
Thus, the correct answer is (A).