A rod PQ of mass M and length L is hinged at end P. The rod is kept horizontal by a mass less string tied to point Q as shown in figure. When string is cut, the initial angular acceleration of the rod is :

A

$$\frac{2g}{3L}$$

B

$$\frac{3g}{2L}$$

C

$$\frac{g}{L}$$

D

$$\frac{2g}{L}$$