Answer:
Oxygen
Explanation:
The formula for cellular respiration is oxygen + glucose -> water, carbon dioxide, energy. You can already cross out A and D because they aren't in the formula, so you have two left, water and oxygen. The reason why it is oxygen and not water is because without oxygen you can't even have water. also, I just got this right on my test :-)
True - The weight of an object is equal to the force of gravity acting upon the object. .... A contact force results from the physical contact between two objects.
C. Channel proteins bind to molecules too large to diffuse into or out of the cell, and allow them to pass.
D. which is also known as osmosis a form of facilitated diffusion (doesn't require energy)