This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': '"Air crescent" sign is seen in \nSelect and explain. \nA. Hydatid cyst, B. Aspergillosis, C. Tuberculosis cavity, D. Amoebic liver abscess', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "Air crescent" sign is seen in fungal ball or aspergilloma in a tubercular cavity. Ref ganong\'s review of medical physiology 25e 765', 'role': 'assistant'}]