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': 'Which is not a Vapour phase disinfectants \nSelect and explain. \nA. Ethylene oxide, B. Thiomersal, C. Formaldehyde gas, D. Betapropiolactone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Vapour phase disinfectants - Ethylene oxide, Formaldehyde gas, BPL.', 'role': 'assistant'}]