This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'An epidemiological investigation undertaken to test the hypothesis regarding the causation of a disease is called \nSelect and explain. \nA. Case control study, B. Cohort study, C. Prospective study, D. Descriptive study', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]