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': 'Repetition of a study in a given group is \nSelect and explain. \nA. Panel study, B. Cohort study, C. Group study, D. High risk', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]