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
Which of the following is a die hardener 
Select and explain. 
A. Cyanoacrylate., B. Potassium sulphate., C. Sodium chloride., D. Resin
A: Cyanoacrylate.
Answer: A: Cyanoacrylate. 
Explanation: Die hardeners arc materials used to reinforce the surface of a die so as to make it more resistant of abrasion and scratching.
Die hardeners used with gypsum dies:
• Cyanoacrylate
• Silver plating
• Addition of die hardeners to gypsum