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
The dye used in the "Reductase enzyme" (caries activity
test) is 
Select and explain. 
A. Diazoeresorcinol, B. Bromocresol green, C. 1% acid red in propylene glycol, D. Methyl blue
A: Diazoeresorcinol
Answer: A: Diazoeresorcinol 
Explanation: None