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 setting time of ZnPO4 cement can be retarded by 
Select and explain. 
A. mixing more powder to the liquid, B. mixing powder to liquid, checked by water, C. slower addition of powder to liquid, D. faster addition of powder to liquid
C: slower addition of powder to liquid
Answer: C: slower addition of powder to liquid 
Explanation: None