I believe the correct answer from the choices listed above is the third option. It is oxygen that is a necessary reactant for cellular respiration to occur. Cellular respiration, in a sense, is breaking down sugar in the presence of oxygen. Hope this answers the question.
Where the optic nerve exits the back of the eye
Answer:
So as the mass of either object increases, the force of gravitational attraction between them also increases. ... Since gravitational force is inversely proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitational forces.
Explanation:
It protects the spinal cord.
gradpoint homies.