Answer:
Option B
Explanation:
$s=t^{3}-12t^{2}+6t+8$
$\frac{ds}{dt}=3t^{2}-24t+6$
$\frac{d^{2}s}{d^{2}t}=6t-24$
Acceleration =0
$\Rightarrow$ 6t-24=0
$\therefore$ t=4
Required velocity = $\frac{ds}{dt}]_{t=4}$
$=3\times (4)^{2}-24\times 4+6$
=48-96+6=42 units