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: ENT
[{'content': 'Surface area of tympanic membrance - \nSelect and explain. \nA. 55 mm2, B. 70 mm2, C. 80 mm2, D. 90 mm2', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]