If a phenomenon changes over time, what kind of research should be undertaken to study it?

Correct option is B

The correct answer is (b); Longitudinal Research
Longitudinal research is specifically designed to study changes in phenomena over time. This type of research involves repeated observations of the same variables (e.g., individuals, groups) over short or long periods and is particularly useful for understanding dynamics, development, and change. It allows researchers to detect developments or changes in the characteristics of the target population at different points in time.