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
Silica whose inversion temperature is below fusion temperature 
Select and explain. 
A. Cristoballite, B. Tridymite, C. Silica, D. Fused Quartz
D: Fused Quartz
Answer: D: Fused Quartz 
Explanation: None