A light rod of length 1 m is pivoted at its centre and two masses 5 kg and 2 kg are hung from the ends as shown. The critical angular acceleration of the rod if it is assumed to be massless is?

Question

$$\begin {array} {1 1} (a)\;\frac{6g}{7} & \quad (b)\;\frac{5g}{4} \\ (c)\;\frac{3g}{2} & \quad  (d)\;\frac{2g}{3} \end {array}$$