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': 'Which of the following impression materials is easy to pour and difficult to remove the stone cast from the impressions? \nSelect and explain. \nA. Addition polysilicone, B. Condensation polysilicone, C. Polyether, D. Polysulfide', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]