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': 'Marginal leakage due to temperature changes commonly seen in \nSelect and explain. \nA. Amalgam alloy, B. Unfilled resin, C. filled resin, D. Gold alloy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]