The answer is letter c. produces protein. <span>Water, ions and molecules requires for cellular processes, can leave and
enter cells through a passive process like diffusion. Diffusion is random
movement of molecules yet has a net direction to regions of lower concentration
in order to reach a balance. Simple passive diffusion takes place when small
molecules pass through the lipid bi-layer of
a cell membrane. Depending on carrier proteins, facilitated diffusion is
imbedded to allow certain substances to pass through, which may not be able to
diffuse through cell membrane.</span>
