Which statement about osmosis is correct?

• A. Osmosis requires energy input.
• B. Osmosis moves solutes from high to low concentration.
• C. Osmosis is the diffusion of water across a selectively permeable membrane.
• D. Osmosis occurs only in plants.

Answer: (C)

Osmosis is the passive diffusion of water across a selectively permeable membrane. Water moves from areas of higher water potential (lower solute concentration) to areas of lower water potential (higher solute concentration) through the membrane, until equilibrium is reached. Because this is a passive process, it does not require energy input. The membrane's selective permeability lets water pass while restricting many solutes, which is why osmosis specifically describes water movement. This process happens in all cells, not just in plants.

That statement describes osmosis accurately because it names water diffusion across a selectively permeable membrane. It isn’t driven by energy, it isn’t about solutes moving, and it isn’t limited to plants.