In the figure shown `m_(1)=1 kg,m_(2)=2kg`, pulley is ideal. At `t=0`, both masses touches the ground and string is taut. A force `F=2t` is applied to pulley (t is in second) then `(g = 10 m//s^(2))` :
A. `m_(2)` is lifted off the ground at `t=20` sec
B. acceleration of pulley when `m_(2)` is about to lift off is `5 m//s^(2)`
C. `m_(1)` is lifted off the ground at `t=0` sec
D. both blocks are lifted off simultaneously
