How does the viscosity of a fluid being pumped affect the operation of a spur gear pump?

Correct Answer: Option B — The viscosity of the fluid is relatively unimportant in the pump operation.

Spur gear pumps are positive displacement machines designed to move a specific volume per revolution regardless of fluid viscosity. While extremely high viscosity may increase power requirements or cause cavitation, the fundamental pumping mechanism remains consistent across a wide range of fluid viscosities, making the pump's operation relatively independent of it.