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
Which of the following refractory is used to counteract most of the expansion 
Select and explain. 
A. Quartz, B. Cristobalite, C. Tridymite, D. Corundum
B: Cristobalite
Answer: B: Cristobalite 
Explanation: None