The correct option is A WP
Wall pressure (WP) is pressure exerted by the cell wall on the cell membrane in a fully turgid cell. It is generally equal and opposite to turgor pressure except in a plasmolysed cell.
Turgor pressure (TP) is the pressure exerted by the swelling protoplast on its walls due to the osmotic entry of water into it.
Diffusion pressure (DP) is the pressure exerted by the molecules that are undergoing diffusion.
The pressure that is required to prevent water from diffusing or undergoing osmosis in spite of a difference in water potentials, is called osmotic pressure (OP).