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': 'Incidence of C shaped canal is maximum for: \nSelect and explain. \nA. Mandibular 1st molar, B. Mandibular 2nd molar, C. Maxillary 1st premolar, D. Maxillary 1st molar', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Some C-shaped canals are difficult to interpret on radiographs and often are not identified until an endodontic access is made.\xa0\nThese are commonly seen in mandibular second molars and maxillary first molars,\xa0especially when roots of these teeth appear very close or fused.', 'role': 'assistant'}]