b
\(\begin{array}{l}
{M_A} = 1\,kg,\,{M_B} = 3kg\\
{\mu _{AB}} = 0.2\\
{\mu _B} = 0.2\\
{F_{\max }} = \left( {{M_A} + {M_B}} \right) \times 0.2 \times 10\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \left( {{M_A} + {M_B}} \right) \times 0.2 \times \\
\,\,\,\,\,\,\,\,\,\,\, = 4 \times 2 + 4 \times 2 = 16
\end{array}\)
