After cutting cucumber if salt is added, then water comes out due to

The release of water from a cucumber after adding salt is caused by osmosis. When salt is applied, the external environment becomes hypertonic, meaning it has a higher solute concentration than the fluid inside the cucumber cells. Consequently, water moves from the area of higher water potential (inside the cells) to the area of lower water potential (outside) through the semi-permeable cell membranes to reach equilibrium. This specific movement of water out of the cell is called exosmosis.

While osmosis is a form of passive transport and a specific type of diffusion, it is the most accurate term for the movement of a solvent across a membrane. Active transport is incorrect as it requires energy (ATP) to move substances against a concentration gradient, which is not the case here.