The correct option is A increases
Water potential (ψ w) is the potential energy of the water due to its water molecules. The greater the concentration of water in a system, the greater is its water potential.
Endosmosis is the movement of the water inside the cells when the cell is placed in a hypotonic solution.
Due to entry of water inside the cell by endosmosis, the concentration of water molecules inside the cell increases and hence, the water potential also increases.