A uniform disc of radius R and mass M is free to rotate only about its axis. A string is wrapped over its rim and a body of mass m is tied to the free end of the string as shown in the figure. The body is released from rest. Then the acceleration of the body is :

Question

$\begin{array}{1 1}(1)\; \frac{2 mg}{2m + M} \\ (2)\; \frac{2 Mg}{2m + M} \\ (3)\; \frac{2 mg}{2M + m} \\ (4)\; \frac{2 Mg}{2M + m} \end{array}$