Figure shows two block `A` and `B` pushed against the wall with the force `F` . The wall is smooth but the surfaces in contact of `A` and `B` are rough. Which of the following is true for the system of blocks to be at rest againts wall?
A. F should be be more than the weight of A and B
B. F should be equal to the weight of A and B
C. F should be less than the weight of A and B
D. sysem cannot be in equilibrium