The movement of which kind of molecules is controlled by osmosis?

The correct answer is water.  

Osmosis refers to the motion of the free water molecules through a semi-permeable membrane down a concentration gradient. The free water molecules refers to the ones, which are not associated with the solute particles, like the salt ions.  

Similar to the diffusion of the other kinds of molecules, the osmosis leads to a net difference in the concentration of water via a membrane, that is, an important activity of the biological species.  

the electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, x-rays, and gamma-rays.

when it is at an intermediate population density