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': 'A 6 year old child does not have any permanent tooth erupted in oral cavity. By what maximum age the tooth should erupt normally? \nSelect and explain. \nA. 7.5 years, B. 8.5 years, C. 6.5 years, D. all of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]