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': "Thornwaldt's cyst is \nSelect and explain. \nA. Laryngeal cyst, B. Nasopharyngeal cyst, C. Ear cyst, D. None", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]