If a particle is moving on an elliptical path given by $\vec{r}=b \cos \omega t \hat{1}+a \sin \omega t^{n}$, then its radial acceleration along
$\vec{r}$ is :
(a) $\omega \overrightarrow{\mathrm{r}}$
(b) $\omega^{2} \vec{r}$
(c) $-\omega^{2} \overrightarrow{\mathbf{r}}$
(d) none of these