A rigid massless rod of length $$3l$$ has two masses attached at each end as shown in the figure. The rod is pivoted at point P on the horizontal axis. When released from the initial horizontal position, its instantaneous angular acceleration will be:

A

$$\frac{g}{2l}$$

B

$$\frac{7g}{3l}$$

C

$$\frac{g}{3l}$$

D

$$\frac{g}{13l}$$