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
An example for disclosing solution is 
Select and explain. 
A. Chlorhexidine, B. Mercurochrome preparations, C. Quaternary Ammonium compound, D. Sorbitol
B: Mercurochrome preparations
Answer: B: Mercurochrome preparations 
Explanation: None