Answer:
The correct answer is:
case-study research (a.)
Explanation:
A case study research is applied in life and social sciences to obtain an in-depth and detailed examination of a single individual or case. A case is any unit of analysis, including individuals, events, organization or an action.
Case studies can be single or multiple case studies. In medicine, as in this our example, a case study can be a finding or examination reported on a particular individual. It also finds application in sociology, psychology, anthropology, politics etc.
When selecting a case study, typical and average cases are most often not ideal, but cases with unusual results or patterns are selected, hence, unlike random sampling used in subject selection in the survey research, information-oriented sampling method is used in selecting cases in case studies. The case studies effectively seeks to compare the effects of the subject (practical cases) with the object (theoretical cases). Hence, three types of cases are selected in case studies, they include; key cases, outlier cases and local knowledge cases.
Key cases are those cases that are chosen based on the peculiarity of the circumstances surrounding such cases.
Outlier cases are extreme or atypical cases that defile normalcy hence arouse interest.
Local knowledge cases are those cases for which the researcher has local theoretical knowledge of, hence set out to go for in-depth probe.
