Solve this:

Q. In the given arrangement the maximum value of F for which there is no relative motion between the blocks
 
                             

    $$\begin{gathered} \left(1\right) {\mathrm{\mu m}}_1{\mathrm{g}}_{ } \left(2\right) \mathrm{\mu }\left({\mathrm{m}}_1+{\mathrm{m}}_2\right)\mathrm{g} \\ \left(3\right) {\mathrm{\mu m}}_1\mathrm{g} {\left(\frac{{\mathrm{m}}_1}{{\mathrm{m}}_2}+1\right)}_{ } \left(4\right) \mathrm{Zero} \end{gathered}$$