The bob of a simple pendulum having length ' $\ell$ ' is displaced from its equilibrium position by an angle of $\theta$ and released. If the velocity of the bob, while passing through its equilibrium position is $\mathrm{v}$, then $\mathrm{v}=\ldots \ldots \ldots$
(A) $\sqrt{\{2 g \ell(1-\cos \theta)\}}$
(B) $\sqrt{\{2 g \ell(1+\sin \theta)\}}$
(C) $\sqrt{\{2 g \ell(1-\sin \theta)\}}$
(D) $\sqrt{\{2 g \ell(1+\cos \theta)\}}$