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 of zinc phosphate is accelerated by: 
Select and explain. 
A. Adding a drop of water, B. Increasing mixing time, C. Cooling the slab, D. Adding a drop of oleic acid
A: Adding a drop of water
Answer: A: Adding a drop of water 
Explanation: None