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': 'Operation theatres are sterilized by - \nSelect and explain. \nA. Carbolic acid spraying, B. Washing with soap and water, C. Formaldehyde, D. ETO gas', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]