The correct answer is c) osmosis.
Osmosis is the specific term used to describe the movement of water across a semipermeable membrane. In osmosis, water molecules move from an area of lower solute concentration to an area of higher solute concentration until equilibrium is reached. This process does not require energy, which distinguishes it from active transport that does need energy to move substances against their concentration gradient.
While facilitated diffusion also involves transport across a membrane, it typically refers to larger or polar molecules moving through protein channels and generally does not apply to water specifically. Thus, option c is the most accurate choice in this context.