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: Dental
[{'content': 'Chlorhexidine used for hand disinfection uses\nconcentration \nSelect and explain. \nA. 1%, B. 0.50%, C. 0.20%, D. 0.12%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]