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 product, which is obtained by calcining gypsum under steam pressure at 120-130°C or by dehydrating gypsum in the presence of sodium succinate, is 
Select and explain. 
A. Alpha - hemihydrates, B. Beta - hemihydrates, C. Calcium sulphate dihydrate, D. Orthorhombic anhydrate
A: Alpha - hemihydrates
Answer: A: Alpha - hemihydrates 
Explanation: None