Which definition best matches osmosis in physiological systems?

• A. The random Brownian motion of solute molecules that results in their accumulation where they are produced rather than their net movement toward regions of lower water concentration
• B. The active transport of solutes across membranes using ATP to move solutes from low to high concentration against their gradients
• C. The diffusion of water across a semipermeable membrane from an area of lower solute concentration (higher water) to an area of higher solute concentration (lower water)
• D. The convective bulk flow of plasma proteins from the vascular compartment into the interstitial space driven by hydrostatic pressure

Answer: (C)