The displacement of a particle varies with time as $x=12 \sin \omega t-16 \sin ^{3} \omega t$ (in $\left.\mathrm{cm}\right) .$ If its motion is
SHM, then its maximum acceleration is :
(a) $12 \omega^{2}$
(b) $36 \omega^{2}$
(c) $144 \omega^{2}$
(d) $\sqrt{192} \omega^{2}$