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 occlusal outline of the permanent mandibular first molar is usually similar to \nSelect and explain. \nA. Circle, B. Square, C. Trapezoid, D. Parallelogram', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]