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 ranking of tear strength from the lowest to highest of all impression materials generally is as follows: \nSelect and explain. \nA. Hydrocolloids, silicones, polyether, polysulfide, B. Silicones, hydrocolloids, polyether, polysulfide, C. Polysulfide, hydrocolloids, silicones, polyether, D. Hydrocolloids, polyether, silicones, polysulfide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Tear strength is an important property for some materials such as impression materials; the impression must be removed from the undercuts without distortion or tearing of the edges. This\xa0 resistance\xa0to\xa0tearing is known as tear strength. Polysulﬁde impression materials have high tear strength that allows them to be removed from undercuts without tearing.\nHydrocolloids, on the other hand, lack adequate tear strength. Hence, to prevent tearing, most impressions have to be removed with a snap motion, parallel to the long axis of the teeth.', 'role': 'assistant'}]