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 child has 12 permanent and 12 deciduous teeth, what could be his age: \nSelect and explain. \nA. 9 years, B. 11 years., C. 5 years., D. 15 years.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]