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 main difference between dental stone and dental plaster is: \nSelect and explain. \nA. Chemical composition, B. Self life, C. Shape and size of particles, D. Solubility in water', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]