A block is over a plank . The coefficient of friction between the block and the plank id `mu=0.2 `Initially both are at rest , suddenly the plank starts moving with accleration `alpha_(0)=4m//s^(2)` The displacement of the block in s is `(g=10m//s^(2))`
A. 1m relative to ground
B. 1 m relative to plank
C. zero relative to plank
D. 2 m relative to ground