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: Microbiology
[{'content': 'ULPA filters are used to disinfect \nSelect and explain. \nA. Water, B. Air, C. Urine, D. Blood', 'role': 'user'}, {'content': 'Answer: B \nExplanation: ULPA (Ultra - low Particulate / penetration air filters)', 'role': 'assistant'}]