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': 'Gypsum product having least expansion: \nSelect and explain. \nA. Impression plaster, B. Model plaster, C. Stone plaster, D. Die stone', 'role': 'user'}, {'content': 'Answer: D \nExplanation: DENTAL STONE, HIGH STRENGTH (TYPE IV)\nThe principal requisites for a die material are strength, hardness, and minimal setting expansion. To obtain these properties, modified α-hemihydrate is used. The cube-shaped particles and the reduced surface area produce such properties without undue thickening of the mix. This material is also called die stone.', 'role': 'assistant'}]