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
Modifiers are added to gypsum mainly to 
Select and explain. 
A. Modify setting time, B. Modify setting expansion, C. Modify strength, D. Decrease the porosity
A: Modify setting time
Answer: A: Modify setting time 
Explanation: None