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: Social & Preventive Medicine
[{'content': '9 families surveyed have 1, 2,2, 2,3,4, 4, 6, 7 children respectively. The mean, median, mode respectively are - \nSelect and explain. \nA. 3.4., 2, 3, B. 3,2,3, C. 3,3,3, D. 3.4,3,2', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]