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:

• A

  $\frac{2 Mg}{2m+M}$
• B

  $\frac{ \mathrm{2\; M}g}{2M+m}$
• C

  $\frac{2 mg}{2M+m}$
• Correct answer
  D

  $\frac{2 mg}{2m+M}$

Hence, the correct answer is option: 'D'.