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 Co-Cr alloy, function of chromium is to provide \nSelect and explain. \nA. Increase in corrosion resistance, B. Increases strength, C. Increased toughness, D. Increase flexibility', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]