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 expansion of gypsum products can be reduced by: \nSelect and explain. \nA. Increased spatulation, B. Adding potassium sulfate, C. Less water powder ratio, D. Allowing setting under water', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]