Answer: 4. the blood coming into the lungs is high in co2 and low in 02 so the gasses diffuse from a higher to a lower concentration in this area.
Step-by-step explanation:
diffuson is the process whereby gasses travel from an area of high concentration to an area of lower concentration. with that being said, in the diagram, it is clear that co2 is diffusing out of the blood, which means that there's a high concentration of co2 in the blood, which is why it is coming out. The same with o2, it is going in because there is a low concentration of it in the blood and high in the lungs.