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 Single rooted tooth will most commonly have 2 root canals \nSelect and explain. \nA. Upper Central incisor, B. Upper 2nd premolar, C. Lower 1st premolar, D. Lower Central incisor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]