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': 'In base metal alloys, corrosion resistance occurs due to \nSelect and explain. \nA. Passivity, B. High fusion temperature, C. High molecular weight, D. Co-efficient of thermal expansion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]