On a uniform rod of length l and mass M, two identical masses m are kept at the extreme ends. What is the moment of inertia of the system about an axis passing through its center and perpendicular to its length ?

Question

$$\begin {array} {1 1} (a)\;\frac{(M+6m)l^2}{12} & \quad (b)\;\frac{(M+6m)l^2}{3} \\ (c)\;\frac{Ml^2}{12}+\frac{ml^2}{6} & \quad  (d)\;\frac{Ml^2}{12}+2 ml^2 \end {array}$$