Answer:
(B) Retrospective cohort
Step-by-step explanation:
Retrospective cohort studies: The retrospective cohort studies are one of the types of observational research studies including the researchers to look back in time or past at self-report or archived data to investigate the difference in the risk of disease between exposed and non-exposed patients.
Cohort studies are better than case-control studies because they are generally prospective. The cohort studies are inexpensive to carry-out.
In the question above, the statement signifies the retrospective cohort study.