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
Set white MTA  can be dissolved by the adjunct solution of: 
Select and explain. 
A. Carbonic acid., B. Normal saline., C. Sodium hypochlorite., D. Hydrogen peroxide.
A: Carbonic acid.
Answer: A: Carbonic acid. 
Explanation: Carbonic acid can be effectively used as an adjunct to dissolve set white MTA even after 21 days.