The correct answer is - option D. epidemiological studies.
Explanation:
Epidemiology studies are the that include research, researchers use the surveys, interviews, and measurements to study larger cohorts of people.
The aim is to recognize and study the relationship between potential risk factors and health or disease over a period of time. It is helpful to find out how often an individual can occur in various groups of people.
Thus, the correct answer is - option D. epidemiological studies.
