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': 'Disinfection of the rooms can be done by using \nSelect and explain. \nA. 20% phenol, B. High efficiency particle arrestors, C. 40% formaldehyde vapour, D. Chlorine gas', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]