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': 'For air blasting of ceramic veneer the particle size of alumina is used \nSelect and explain. \nA. 25 micrometer, B. 50 micrometer, C. 75 micrometer, D. 100 micrometer', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]