$2$ Multiple Choice $10$ points

This is an $a_x-t$ graph for an object in simple harmonic motion. At which of the following times does the object have the most negative velocity $v_x?$

$a_r(\frac{m}{s^2})$

$t=0\mathrm{.}10s$

$t=0\mathrm{.}15s$

$t=0\mathrm{.}20s$

$t=0\mathrm{.}25s$

Two of the above are tied for most negative displacement.