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': 'The average width of enamel rods is \nSelect and explain. \nA. 10 microns, B. 5 microns, C. 2 microns, D. 0.5 microns', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]