Osmosis deals only with D. Water. Diffusion and Osmosis are relatively the same thing besides the fact that water is largely incorporated with the osmosis.
GPE is the gravitational Potential Energy which is given by mgh.
mg is the gravitational force(a force) and h is the height of the object(or distance of the object from earth's surface)
SO GPE = mg (force) x h (distance)
The 4 main one are Iron, oxygen, silicon, and magnesium<span />
I just took that quiz , it’s A