Answer:
D. Case-Control Study
Step-by-step explanation:
Case-Control Study: This study is also referred to as a case-referent study. The case-control study is one of the types of observational study that compares two different groups that vary in the outcome are compared and identified based on some causal attribute. It determines the process of exposure-related or associated with a particular outcome, for example, disease. In a case-control study, the cases and the controls are being identified and compared retrospectively.