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: Forensic Medicine
[{'content': 'At the age of 9 years, the number of permanent teeth is - \nSelect and explain. \nA. 12, B. 16, C. 20, D. 24', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Number of permanent teeth (between 6-11 years) = (Age in years -5) x 4\nSo, number of permanent teeth at 9 years = (9-5) x 4 = 16', 'role': 'assistant'}]