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': 'Most important part of RPD is: \nSelect and explain. \nA. Base, B. Connector, C. Reciprocal arm, D. Replaced took', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]