Three blocks are stacked vertically as shown in the image. The masses of the blocks A, B, and C are 20 kg, 15 kg, and 8 kg respectively. The coefficient of friction between A and B is 0.4, and between B and C and C and the ground is 0.35. Determine the minimum force P that would be required for block B to begin moving. [NB: Marks are allocated for drawing FBDs].