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': 'Lower primary 1st molar has \nSelect and explain. \nA. 3 pulp horns and 3 root canals, B. 4 pulp horns and 3 root canals, C. 4 pulp horns and 4 root canals, D. 3 pulp horns and 4 root canals', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]