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': 'Closing of midline diastema by using a removable appliance \nSelect and explain. \nA. Reciprocal single simple anchorage, B. Reciprocal simple compound anchorage, C. Reciprocal stationary single anchorage, D. Reciprocal stationary compound anchorage', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]