Answer:
Case study.
Step-by-step explanation:
Case study may be defined as one of the research method that includes the depth and detailed study of the particular subject or case. The formal research methods are used in the case study.
The individual has memory that can memorize of the date events. The psychologist can do the case study of that individual by including the brain scans and memory tests. The case study is useful to find the research method in case of this individual.
Thus, the correct answer is option (d).