Two blocks of masses m and M are placed on a horizontal frictionless table connected by light spring as shown in the figure . Mass M is pulled to the right with a force F. If the acceleration of mass m is a, then the acceleration of mass M will be

• A

  $\frac{(\mathrm{F}-\mathrm{ma})}{\mathrm{M}}$

• B

  $\frac{(\mathrm{F}+\mathrm{ma})}{\mathrm{M}}$

• C

  $\frac{\mathrm{F}}{\mathrm{M}}$

• D

  $\frac{\mathrm{am}}{\mathrm{M}}$