Answer:
Cohort study
Step-by-step explanation:
Cohort study: The cohort study is defined as a longitudinal study that takes a sample of cohort that performs a cross-section at different intervals concerning time.
In this context, the cohort is known as a particular group of individuals who incorporates a defining character, usually those individuals who have accomplished a specific event in a particular period, like birth order.
Cohort study comes under the observational studies.
Example: In the question above the researcher wants to identify the impact of cholesterol on the development of heart disease.