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: Dental
[{'content': 'Preventive and interceptive orthodontics is no longer viable after eruption of: \nSelect and explain. \nA. Permanent second molars, B. Primary second molars, C. Permanent first molar, D. Permanent lateral incisors', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]