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': 'According to the type of movement of the anchorage unit, it can be classified as all except \nSelect and explain. \nA. Simple, B. Compound, C. Reciprocal, D. Stationary', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]