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: Surgery
[{'content': 'Poor accessibility is the main disadvantage of _______ flap \nSelect and explain. \nA. Trapezoid, B. Envelope, C. Semilunar, D. Any of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]