Knowing what you know about how a substance travels in diffusion, in order for oxygen to leave the alveoli and enter the blood, there would be
concentration of oxygen in the alveoli compared to the
blood. *
A. higher
B. Lower

the oxygen should be concentrated in the alveoli

Explanation:

Diffusion: The movement of molecules from a region og higher concentration to a region of lower concentration.

So when the Oxygen is concentrated in the alveoli only then it can move towards the blood

Diffusion is a passive transport system which means it doesnt need energy in the form of atp molecules

if the molecules move from a region of lower concentration to a region of higher concentration it needs atp molecules which is energy and is called active transport system

it is either c or d and i know for sure it is not a or b