Which among the following property of the matter is studied in “Rheology”?

Q. Which among the following property of the matter is studied in “Rheology”?
Answer: Viscosity
Notes: Rheology is the study of the flow of matter, primarily in a liquid or gas state. It is related to Viscosity. In the science of rheology, a fluid's changes are measured when there are actual forces (mechanical shear or pump pressure) induced.