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': 'Concentration at which chlorhedixine is bactericidal \nSelect and explain. \nA. 0.05%, B. 0.01%, C. 0.02%, D. 0.02%', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]