The rate of flow of liquid in a tube of radius r, length l, whose ends are maintained at a pressure difference P is \[V=\frac{\pi QP\,{{r}^{4}}}{\eta l}\] where \[\eta \] is coefficient of the viscosity and Q is [DCE 2002]

• A.             8     
• B.             \[\frac{1}{8}\]
• C.             16  
• D.             \[\frac{1}{16}\]