A bob of heavy mass $m$ is suspended by a light string of length $l$. The bob is given a horizontal velocity $v_0$ as shown in figure. If the string gets slack at some point $P$ making an angle $\theta$ from the horizontal, the ratio of the speed $v$ of the bob at point $P$ to its initial speed $v_0$ is:

1. A
   $(\sin \theta {)}^{1/2}$
2. B
   ${\left(\frac{1}{2+3\sin \theta }\right)}^{1/2}$
3. C
   ${\left(\frac{\cos \theta }{2+3\sin \theta }\right)}^{1/2}$
4. D
   ${\left(\frac{\sin \theta }{2+3\sin \theta }\right)}^{1/2}$