The volume of a liquid of density $\mathrm{\rho }$ and viscosity $\mathrm{\eta }$ flowing in time t through a capillary tube of length / and radius R, with a pressure difference P, across its ends is proportional to.

• A

  P ²R²t/$\mathrm{\eta }$l²

• B

  PR⁴/$\mathrm{\eta }$lt

• C

  PR⁴t/$\mathrm{\eta }$l

• D

  $\mathrm{\eta }$R⁴/lt