Answer:
A case study
Explanation:
Case study: In psychology, the term case study refers to one of the research methods which is considered as a descriptive research that is being used by various researchers or experimenters to get an in-depth examination of a group, person, or phenomenon. A case study involves significantly different approaches including psychometric tests, personal interviews, archival records, and direct-observation.
In the question above, the given research method is called a case study.