A block `A` of mass `m` is over a plank `B` of mass `2m`. Plank `B` si placed over a smooth horizontal surface. The coefficient of friction between `A` and `B` is `(1)/(2)`. Blocks `A` is given a velocity `V_(0)` towards right. Then
A. Acceleration of `A` is `(g)/(2)`
B. Acceleration of `A` is `g`
C. Acceleration of `B` relative to `A` is `(3)/(4)g`
D. Acceleration of `A` is zero