A body of mass $m$ is accelerated uniformly from rest to a speed $v$ in a time $t$. The instantaneous power delivered to the body as a function of time is given by
(A) $\frac{m v^{2}}{t^{2}} t^{2}$
(B) $\frac{m v^{2}}{t^{2}} t$
$[2005]$
(C) $\frac{1}{2} \frac{m v^{2}}{t^{2}} t^{2}$
(D) $\frac{1}{2} \frac{m v^{2}}{t^{2}} t$