c. decreased with increasing viscosity of the fluid being filtered.
Explanation:
Filtration is a method of separation which is useful in separating solids from the fluids (either liquids or gases) by adding a specific medium through which only fluid can pass. Fluid which passes through the filter is known as the filtrate.
Increasing the viscosity of the fluid which is being filtered decreases the rate of filtration as the liquid being more viscous take more time to cross the pores of the filter. Thus, rate of filtration is indirectly proportional to the viscosity of the fluid which is being filtered.
