Question

A light, rigid rod with two masses attached to its ends, one of mass 3M and one of mass M, is pivoted about a horizontal axis. The mass 3M is length L from the pivot point and the mass M is length 2L from the pivot point. When released from a horizontal orientation, the rod begins to rotate with an angular acceleration of magnitude...
a) g/(7L)
b) g/(5L)
c) g/(4L)
d) (5g)/(7L)
e) g/L

any help would be greatly appreciated!