Case-control disease is mainly used to identify the factors which are responsible for a disease in a population by comparing a small group of individuals who have that disease with the individuals who do not have that disease but otherwise they are similar.
So here the non-disease individuals are considered and controls. This study plays an important role in studying outbreaks, rare disease, and their outcomes. This study is easy, quick and inexpensive compared to the other epidemiological studies. So the correct answer is a case-control study.
