Answer: Retrospective cohort study
Step-by-step explanation:
Retrospective cohort studies are known as or referred to as the type or kind of observational research under which investigators tend to look back at historical data that is archived in order to examine if risk of the disease was different in between the patients who were exposed and non-exposed. Observational epidemiological designs under which the risk of the disease is retrospectively compared in between the patients which are exposed and non-exposed.