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': 'Impression plaster is: \nSelect and explain. \nA. Less compressive than alginate, B. More compressive than alginate, C. As compressive as alginate, D. More compressive than hydrocolloids', 'role': 'user'}, {'content': 'Answer: A \nExplanation: IMPRESSION PLASTER\nImpression plaster is a β-calcium sulfate hemihydrate used at a water/powder ratio of approximately 0.5 to 0.6. Its fluidity\xa0makes it suitable for making impressions of soft tissues in the uncompressed state, a characteristic of mucostatic impression\xa0material.\xa0\nKey concept: \nImpression plaster is less compressive than Alginate.\nRef: Phillips 12 ed page no 177', 'role': 'assistant'}]