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
[{'content': 'The setting of zinc phosphate is accelerated by: \nSelect and explain. \nA. Adding a drop of water, B. Increasing mixing time, C. Cooling the slab, D. Adding a drop of oleic acid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]