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': '5th cusp is usually not seen in: \nSelect and explain. \nA. Mandibular 1st molar, B. Mandibular 2nd molar, C. Mandibular 3rd molar, D. Maxillary 1st molar', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]