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: Surgery
[{'content': 'Ethyl alcohol is effective (against spores) \nSelect and explain. \nA. 70%, B. 60%, C. 50%, D. 100%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]