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
True regarding gypsum bonded investments is: 
Select and explain. 
A. After dehydration all forms of gypsum shrink between 200-400 degree Celsius., B. Between 400-700 degree Celsius a slight expansion is noted., C. Lateral shrinkage in gypsum is caused due to decomposition and release of sulphur dioxide., D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: After dehydration all forms of gypsum shrink between 200-400° C.
Between 400 and 700° C, a slight expansion is noted.
Lateral shrinkage in gypsum is caused due to the decomposition and the release of sulfur dioxide.
It is imperative, that gypsum investment should not be heated above 700° C.

Phillip’s 12th edition page 201