A block of mass m, lying on a rough horizontal plane, is acted upon by a horizontal force P and another force Q, inclined at an angle $\mathbf{\theta }$ to the vertical upwards. The block will remain in equilibrium, if minimum coefficient of friction between it and the surface is

• A

  $\frac{(P+Q\sin \theta )}{(mg-Q\cos \theta )}$

• B

  $\frac{(P\cos \theta +Q)}{(mg-Q\sin \theta )}$

• C

  $\frac{(P-Q\cos \theta )}{(mg+Q\sin \theta )}$

• D

  $\frac{(P\sin \theta -Q)}{(mg-Q\cos \theta )}$