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': 'Linear coefficient of thermal expansion of metal used for metal ceramic restoration range from: \nSelect and explain. \nA. 11.5-12.5 x 10-6/°C, B. 10.5-11.5 x 10-6/°C, C. 13.5-14.5 x 10-6/°C, D. 16.5-17.5 x 10-6/°C', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Most\xa0porcelains\xa0have\xa0coefficients\xa0of\xa0thermal\xa0expansion\xa0between\xa013.0\xa0and\xa014.0\xa0×\xa010 −6 /°C, and\xa0metals\xa0between\xa013.5\xa0and\xa014.5\xa0×\xa010 −6 /°C.\xa0The difference\xa0of\xa00.5\xa0×\xa010 −6 /°C\xa0 in\xa0 thermal\xa0 contraction between\xa0metal\xa0and\xa0porcelain\xa0causes\xa0the\xa0metal\xa0to contract slightly more than does the ceramic\xa0during cooling. This condition places the porcelain under slight residual compression, which makes it less sensitive to the tensile stresses induced by mechanical loading.\nCraig’s Restorative dentistry 14 ed page 222', 'role': 'assistant'}]