Answer:
I think it is D.
Explanation:
People who have a fast metabolism dont need it so whats the point, and the others are just random.
Carbon Dioxide (or CO2) is produced by the lungs I think because when you inhale, you breathe in oxygen, then you exhale the carbon dioxide in the lungs. That's actually 3 and 4. As for number 2, I want to say either the alvioli or however that's spelled but technically, the entire body uses oxygen so I'm not sure.
Answer:
Osmosis:The movement of solute across a semi-permeable membrane
Cell membrane:It is a semi-permeable allowing the movement of water and nutrients to move in and out of the cell.
