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': 'Which primary tooth has longest duration of function \nSelect and explain. \nA. mandibular canine, B. maxillary canine, C. mandibular 2nd molar, D. maxillary 2nd molar', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Maxillary Permanent canine has the longest duration of function and is last to shed off. One of the reasons is its long root.', 'role': 'assistant'}]