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': 'Amalgam exhibits a Poisson’s ratio of \nSelect and explain. \nA. 0.3, B. 0.5, C. 0.6, D. 1', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most\xa0rigid\xa0materials,\xa0such\xa0as\xa0enamel,\xa0dentin,\xa0amalgam, and dental composite, exhibit a Poisson’s\xa0ratio of about 0.3. Brittle substances such as hard gold\xa0alloys\xa0and\xa0dental\xa0amalgam\xa0show\xa0little\xa0 permanent\xa0reduction in cross section during a tensile test.\nMore\xa0ductile materials such as soft gold alloys, which are\xa0high in gold content, show a higher degree of reduction\xa0in\xa0cross-sectional\xa0area\xa0and\xa0higher\xa0Poisson’s\xa0ratios.\xa0\nRubber\xa0has\xa0a\xa0Poisson’s\xa0ratio\xa0of\xa0nearly\xa00.5.\xa0\nCork exhibits little lateral expansion under compression and has a Poisson’s ratio close to 0.\xa0\nThis property has made cork a common material for sealing wine bottles.\nRef:Craig’s Restorative Dentistry ed 14th pg 36', 'role': 'assistant'}]