Out of the following functions representing motion of a particle which represents SHM : <br> (A) $y = \sin \omega t - \cos \omega t $ <br> (B) $ y = \sin^3 \omega t $ <br> (C) $ y = 5 \cos (\frac{3 \pi}{4} - 3 \omega t)$ <br> (D) $ y = 1 + \omega t + \omega^2 t^2$
