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': 'Minimum thickness for type I zinc phosphate cement should be \nSelect and explain. \nA. 15 microns, B. 25 microns, C. 50 microns, D. 100 microns', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]