The correct answer is option 3: Osmosis.

Osmosis is the process by which water molecules move from an area of lower solute concentration (dilute solution) to an area of higher solute concentration (concentrated solution) through a selectively permeable membrane. The selectively permeable membrane allows the passage of water molecules but restricts the movement of solute particles.

Option 1: Diffusion is the net movement of solute particles from an area of higher concentration to an area of lower concentration. While osmosis involves the movement of water molecules, diffusion involves the movement of solute particles.

Option 2: Dispersion refers to the spreading or scattering of solute particles in a medium. It is not directly related to the movement of water through a selectively permeable membrane.

Option 4: Absorption is the process by which substances are taken up and incorporated into a different material. It does not specifically refer to the movement of water through a selectively permeable membrane.

Therefore, the best option that describes the net movement of water from a dilute to a concentrated solution through a selectively permeable membrane is osmosis.