Answer:
The correct answer is a. the comparative approach.
Explanation:
In the comparative method, we do the comparison between two different values, groups, cultures, etc. In a comparative approach, the similarities and differences are checked between two things to draw a conclusion.
Comparative study helps in finding out the relationship between two subjects. It can be used for hypothesis testing and theory building. Comparative study is and can be used in every field. So the study of biological processes by comparing different species is known as comparative study.