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': 'Tooth with most variable occlusal anatomy: \nSelect and explain. \nA. Maxillary third molar, B. Mandibular third molar, C. Maxillary second premolar, D. Mandibular second premolar', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]