In the context of passive transport, which statement best describes how diffusion works in cells?

• A. Movement of water across a selectively permeable membrane from lower solute concentration to higher solute concentration, driven by osmotic pressure.
• B. Movement of molecules from a region of lower concentration to a region of higher concentration using ATP-powered membrane pumps.
• C. Net movement of molecules from a region of higher concentration to a region of lower concentration due to random thermal motion, without requiring cellular energy input.
• D. Vesicle-mediated transport that imports extracellular material into the cell via membrane invagination.

Answer: (C)