Concept:Osmosis is the movement of water molecules through a selectively permeable membrane from a dilute solution to a more concentrated solution.Explanation:In selective reabsorption, useful substances and water are reabsorbed from the kidney tubules into the blood.Water moves back into the blood by osmosis through the selectively permeable walls of the kidney tubules.The other options describe diffusion, active transport, or absorption processes, not specifically osmosis.Answer:A. Selective reabsorption