Answer:
D. Hydrostatics
Step-by-step explanation:
The term hydrostatic is defined as the science of fluids with no motion. In this definition a fluid is a substance that flows continually when a shear stress is applied. A fluid can be liquids or gases.
A fluid at rest can experience shear stresses mainly caused by friction between fluid particles caused by fluid viscosity. Such fluids can not resist this type of stress hence they will move in respond to the shear stress applied.