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': 'Two or more parallel vertical surfaces of abutment teeth shaped to direct the prosthesis during placement and removal, are known as: \nSelect and explain. \nA. Orientation plane, B. Parallel block out, C. Survey lines, D. Guiding planes', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]