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': 'What appears to be the principle problem with the use of gallium alloys as an amalgam substitute? \nSelect and explain. \nA. Less compressive strength, B. More expansion which leads to tooth fracture, C. Poor biocompatibility, D. Loss of corrosive products', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]