The correct choice is (c) Depends on the shear rate
Explanation: Apparent viscosity (sometimes denoted η) is the shear stress applied to a fluid divided by the shear rate. For a Newtonian fluid, the apparent viscosity is constant, and equal to the Newtonian viscosity of the fluid, but for non-Newtonian fluids, the apparent viscosity depends on the shear rate. In such case, the ratio between shear stress and shear rate is not constant; nevertheless, this ratio for non- Newtonian fluids.