Answer:
a. case study
Explanation:
Case study -
It is one of the research method , which involve the complete in - depth study about the particular topic or incident , is referred to as case study .
In case study , all the aspect are considered ,like , anything related to history is taken under consideration , all the medical reports or any other reports are studied.
Case study require lot of study , in complete detail.
Hence, from the given scenario of the question,
The correct term is Case study.
