The lungs deliver a regular supply of oxygen to the blood. which is in turn circulated to most all the cells of the body. at the same time oxygen is consumed during aerobic cellular respiration within these cells. this implies that?

There occurs passive diffusion of oxygen from blood into the cell

Explanation:

This implies that cells take oxygen supply from the blood . The cellular plasma membrane is a permeable membrane that has controlled regulatory mechanism to allow diffusion of oxygen across the cell membrane.

This diffusion mechanism is passively driven from region of high oxygen concentration (outside the cell or in the blood  (body fluid)) to regions of low oxygen concentration (with in the cell membrane)

i think that c)gold was found there

but i am not sure

substitution is the answer in this case