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': 'The name of the sample group of individuals when followed for successive examination to evaluate the effect of oral preventive programmes is: \nSelect and explain. \nA. Panel group, B. Cohort group, C. High risk group, D. Prospective group', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]