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
[{'content': '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 \nSelect and explain. \nA. Alpha - hemihydrates, B. Beta - hemihydrates, C. Calcium sulphate dihydrate, D. Orthorhombic anhydrate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]