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': 'The rate of tarnish and corrosion of class II cast material having VHN 200 is \nSelect and explain. \nA. 0%, B. 2 to 3%, C. 5 to 10%, D. <1%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]