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
Concentration at which chlorhedixine is bactericidal 
Select and explain. 
A. 0.05%, B. 0.01%, C. 0.02%, D. 0.02%
D: 0.02%
Answer: D: 0.02% 
Explanation: None