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': 'Number of teeth at 7 years: \nSelect and explain. \nA. 20, B. 24, C. 26, D. 28', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. 24', 'role': 'assistant'}]