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': 'Which of the following materials has the highest linear coefficient of expansion? \nSelect and explain. \nA. Amalgam, B. Direct gold, C. Tooth structure, D. Composite resin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Composite materials exhibit more dimensional change (2.5 times greater than tooth structure) when subjected to extreme changes in temperature than do the other choices. Direct gold is slightly higher than tooth structure\xa0and amalgam is about twice as high as tooth structure.', 'role': 'assistant'}]