Two blocks with masses M and mare in contact with each other and are resting on a_ horizontal frictionless floor. When horizontal force is applied to the heavier, the blocks accelerate to the right. The force between the two blocks are

A

$$\frac{(M + m)F}{m}$$

B

$$\frac{MF}{m}$$

C

$$\frac{mF}{M}$$

D

$$\frac{mF}{(M + m)}$$