The correct option is C from B to A
We know that,
DPD = OP - TP
In cell A: DPD = 10 - 5 = 5 atm
In cell B: DPD = 15 - 12 = 3 atm
Diffusion pressure deficit (DPD) is the reduction in diffusion pressure (DP) of water in a system over its pure state. Diffusion pressure is the pressure exerted by the molecules that are undergoing diffusion. DP of pure solvent is maximum. DPD determines the direction of movement of water. Water always moves from an area of lower DPD to the area or cell of higher DPD.
In this case cell B has a lower DPD than cell A. Thus, the flow of water will be from cell B to A.