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 refractory is used to counteract most of the expansion \nSelect and explain. \nA. Quartz, B. Cristobalite, C. Tridymite, D. Corundum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]