The steady state velocity ‘V’ of block

Question

A cubic block of side ‘L’ and mass ‘M’ is dragged over an oil film across table by a string connects to a hanging block of mass ‘m’ as shown is fig. The Newtonian oil film of thickness ‘h’ has dynamic viscosity ‘m’ and the flow condition is laminar. The acceleration due to gravity is ‘g’. The steady state velocity ‘V’ of block is:

     (a) $\frac{Mgh}{\mu L^{2}}$                                                                      (b) $\frac{Mgh}{\mu L}$ 

      (c) $\frac{mgh}{\mu L^{2}}$                                                                      (d) $\frac{mgh}{\mu L}$