This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Growth, Development, and Behavior, Subject name: Pediatrics
[{'content': 'At what age the first permanent teeth appear in a child? \nSelect and explain. \nA. 2 years, B. 4 years, C. 6 years, D. 8 years', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., 6 years Rule of six:-* Primary (temporary) dentition begins 6 months.* Secondary (permanent) dentition begins 6 years.Eruption of temporary teeth(Primary dentition)ToothAge in range (months)Average age (months)Lower CI6-87Upper CI7-98Uppler LI7-98Lower LI10-12111 molar12-1413Canine17-1817-5II molar20-3025 Eruption of permanent teeth(Secondary dentition) Age in range (year)Average age (year)First molar6-76[?]5Central incisor7-87Lateral incisor8-98First PM9-1110Second PM10-1211Canine11-1211[?]5Second molar12-1413Third molar17-2517", 'role': 'assistant'}]