A particle moving along x-axis has acceleration $f$, at time $t$, given by $f = f_0 (1 - \frac{t}{T})$, where $f_0$ and $T$ are constants. The particle at t = 0 has zero velocity. In the time interval between $t = 0$ and the instant when $f = 0$, the particle's velocity $(v_x)$ is:

Question

( A ) $f_0T^2$
( B ) $f_0T$
( C ) $\frac{1}{2}f_0T$
( D ) $\frac{1}{2}f_0T^2$