Which of the Following Best Describes Chemical Kinetics

Which of the following best describes chemical kinetics?

A) It is the enthalpy change that occurs when a solid ionic compound is transformed into gaseous ions.
B) It is the process of converting one element to another.
C) It is a methodology that combines chemical reactions and stoichiometric calculations to determine the concentrations of substances present in a sample.
D) It is the study of reaction rates, the changes in the concentrations of reactants and products with time.
E) It is a complete description of the system at a given time, including its temperature and pressure, the amount of matter it contains, its chemical composition, and the physical state of the matter.