Question

when you breathe in, oxygen moves from the air sacs in the lungs into the blood. this happens because there is more oxygen in the lungs than in the blood. which process is the cell membrane using to help maintain homeostasis?
active transport, because it requires energy to move oxygen from the lungs where there is less oxygen to the blood where there is more oxygen
active transport, because proteins are required to move gases
passive transport, because the membrane forces oxygen into the blood
passive transport, because oxygen diffuses from an area of higher concentration to an area of lower concentration

Explanation:

Diffusion is a type of passive transport where substances move from an area of higher concentration to an area of lower concentration without the use of energy. In the lungs, oxygen moves from the air - sacs (higher oxygen concentration) into the blood (lower oxygen concentration), which is an example of passive transport by diffusion. Active transport requires energy and moves substances against the concentration gradient.

Answer:

Passive transport, because oxygen diffuses from an area of higher concentration to an area of lower concentration