Three blocks $A$,$B$,and $C$ of equal mass $m$ are placed on a smooth surface as shown. The coefficient of friction between any two blocks $A$,$B$,and $C$ is $\mu$. The maximum value of mass $M$ of block $D$ such that blocks $A$,$B$,and $C$ move without slipping over each other is:

• A
  $\frac{3m\mu}{\mu + 1}$
• B
  $\frac{3m(1 - \mu)}{\mu}$
• C
  $\frac{3m(1 + \mu)}{\mu}$
• D
  $\frac{3m\mu}{1 - \mu}$