The Time Period for the Rotation of the Conical Pendulum $\theta$

Multiple Choice

The time period for the rotation of the conical pendulum moving in a horizontal circle (bob mass = M,string length L,and vertical half angle $\theta$ ; see figure) is given by the expression:

A) 2 $\pi$ $\times$ {Lcos $\theta$ /g}^1/2
B) 2 $\pi$ $\times$ {Lsin $\theta$ /g}^1/2
C) 2 $\pi$ $\times$ Lcos $\theta$ /g
D) 2 $\pi$ $\times$ Lsin $\theta$ /g
E) {2 $\pi$ $\times$ Lcos $\theta$ /g}^1/2