For Newtonian fluid behaviour, the shear stress exerted by the fluid is equal to the _____.

A

Fluid viscosity divided by the velocity gradient parallel to the direction of shear.

B

Fluid viscosity divided by the velocity gradient perpendicular to the direction of shear.

C

Product of the fluid viscosity and the velocity gradient parallel to the direction of shear

D

Product of the fluid viscosity and the velocity gradient perpendicular to the direction of shear.