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 of the premolars is usually the smallest: \nSelect and explain. \nA. Maxillary first, B. Maxillary second, C. Mandibular first, D. Mandibular second', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]