CGS unit of dynamic viscosity:
Dynamic viscosity is a measure of a fluid's resistance to flow under an applied force or stress. It is defined as the ratio of shear stress to shear rate. The CGS (Centimeter-Gram-Second) system is one of the metric systems of units used to express physical quantities.

The CGS unit of dynamic viscosity is the Poise, which is denoted by the symbol P. It is named after the French physician Jean Louis Marie Poiseuille, who made significant contributions to the field of fluid dynamics.

Explanation:
To understand why the correct answer is option D (Poise), let's briefly look at the other options:

a) Stokes: The Stoke is a unit of kinematic viscosity, not dynamic viscosity. Kinematic viscosity is the ratio of dynamic viscosity to the density of a fluid. It is denoted by the symbol St.

b) Pa-s: The Pascal-second (Pa-s) is the SI unit of dynamic viscosity, not the CGS unit. The SI unit is commonly used in scientific and engineering calculations.

c) m2/s: This is also the SI unit of kinematic viscosity, not dynamic viscosity. It represents the ratio of dynamic viscosity to the density of a fluid.

d) Poise: The Poise is the CGS unit of dynamic viscosity. It is equivalent to 0.1 Pascal-seconds (Pa-s). One Poise is defined as the viscosity of a fluid in which a tangential force of one dyne per square centimeter is required to maintain a velocity difference of one centimeter per second between two parallel layers of the fluid.

Since the question specifically asks for the CGS unit of dynamic viscosity, the correct answer is option D (Poise).

To summarize, the CGS unit of dynamic viscosity is the Poise (P), which is equivalent to 0.1 Pascal-seconds (Pa-s). It is important to understand the units of viscosity to accurately measure and analyze fluid flow in various engineering and scientific applications.