This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Social & Preventive Medicine
[{'content': 'Case control Study is \nSelect and explain. \nA. Backward study, B. Forward study, C. Current study, D. Feature study', 'role': 'user'}, {'content': "Answer: A \nExplanation: (A) Backward study # Case-control is a type of epidemiological study design. Case-control studies are used to identify factors that may contribute to a medical condition by comparing subjects who have that condition (the 'cases') with patients who do not have the condition but are otherwise similar (the 'controls').> Case-control studies are a relatively inexpensive and frequently-used type of epidemiological study that can be carried out by small teams or individual researchers in single facilities in a way that more structured experimental studies often cannot be. They have pointed the way to a number of important discoveries and advances, but their retrospective-backward, non-randomized nature limits the conclusions that can be drawn from them.", 'role': 'assistant'}]