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': 'The "hanging drop appearance in the maxillary sinus radiograph indicates: \nSelect and explain. \nA. A nasal polyp, B. A blow out # of the orbit, C. A radiograph artifact, D. An antrolith', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]