Given below are two statements: One is labelled a Assertion A and the other is labelled as Reason R.
Assertion A: Product of Pressure ($P$) and time ($t$) has the same dimension at that of coefficient of viscosity.
Reason R: $\text{Coefficient of viscosity} = \frac{\text{Force}}{\text{Velocity gradient}}$.
Choose the correct answer from the options given below: