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': 'Size of znpo4 used for luting? \nSelect and explain. \nA. 25 Microns, B. 40 Microns, C. 45 microns, D. 15 Microns', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]