The displacement of a particle along the x-axis is given by $X=a sin^2\omega t$. The motion of the particle corresponds to –

Question

( A ) non simple harmonic motion
( B ) simple harmonic motion of frequency $\frac{\omega}{\pi}$
( C ) simple harmonic motion of frequency $\frac{3\omega}{2\pi}$
( D ) simple harmonic motion of frequency $\frac{\omega}{2\pi}$