A particle is thrown up vertically with a speed $v_1$in air. It takes time ${\mathrm{t}}_1$ in upward journey and  $\left({\mathrm{t}}_2>{\mathrm{t}}_1\right)$ in the downward journey and returns to the starting point with a speed $v_2$. Then:

Figure shows the displacement of a particle moving along $x$-axis as a function of time. The acceleration of the particle is zero in the region.

(a) $AB$

(b) $BC$

(c) $CD$

(d) $DE$

Select correct alternative