Two blocks $A$ and $B$ are placed one over the other on a smooth horizontal surface. The maximum horizontal force that can be applied on lower block $A$, so that $A$ and $B$ move without separation is $49 \mathrm{N}$. The coefficient of friction between $A$ and $B$ is

• A

  $0.2$
• B

  $0.3$
• Correct answer
  C

  $0.5$
• D

  $0.8$

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