Answer:
Cohort study.
Step-by-step explanation:
Cohort study is a type of medical research which is used to identify the cause of disease and relationship between the risk factors and outcomes of health.
Cohort study works on a group of people. This is done by identification of disease and form a hypothesis which causing a disease. They observe the group of people over a specific time period and relate the possible risk factors with the people's health outcomes.