This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Imaging of Alveolar Lung Disease, Subject name: Radiology
[{'content': 'Floating water lily sign is seen in \nSelect and explain. \nA. Aspergillosis, B. Hamartoma, C. Hydatid cyst, D. Cavitating metastasis', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e. Hydatid cyst Separated membranes floating with the cyst give the appearance of water lily.It is pathognomonic of hydatid cyst.", 'role': 'assistant'}]