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: Microbiology
[{'content': 'Least common site of calcified hydatid cyst is ? \nSelect and explain. \nA. Lung, B. Mediastinum, C. Extraperitoneal site, D. Liver', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Lung . The pulmonary hydatid cyst almost never calcify, unlike mediastinal cyst ----> Grainger", 'role': 'assistant'}]