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
The cast should not be stored above: 
Select and explain. 
A. 50° C, B. 55° C, C. 40° C, D. 45° C
B: 55° C
Answer: B: 55° C 
Explanation: If the storage temperature is raised to between 90°C and 110°C (194°F to 230°F), shrinkage occurs, along with loss of strength as the water of crystallization is removed and the dihydrate reverts to the hemihydrate form. As a rule of thumb, it is not safe to store or heat a stone cast in air at a temperature higher than 55°C (130°F). 
Phillips Science of Dental Materials ed 12 pg 192