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 major force producing part of the fixed appliance is: \nSelect and explain. \nA. Bracket, B. Arch wire, C. Lock pin, D. Band', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]