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: Pediatrics
[{'content': 'At what age do first permanent teeth appear ? \nSelect and explain. \nA. 5 years, B. 6 years, C. 7 years, D. 8 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: First primary (milk) tooth erupts at 6 months.\nFirst secondary (permanent) tooth appear at 6 year of age.', 'role': 'assistant'}]