A body of mass $m$, accelerates uniformly from rest to $v_1$ in time $t_1$. The instantaneous power delivered to the body as a function of time $t$ is

Question

( A ) $\frac{mv_1t}{t_1}$
( B ) $\frac{mv_1^2t}{t_1}$
( C ) $\frac{mv_1t^2}{t_1}$
( D ) $\frac{mv_1^2t}{t_1^2}$