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': "A company executive, who travels world wide, presents with upper abdominal mass and + ye casoni's test. The organism is - \nSelect and explain. \nA. Echinococcus, B. Entamoeba histolytica, C. Hepatitis, D. Ascariasis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Echinococcus . Upper abdominal mass and positive casoni's test suggest the diagnosis of hydatid cyst caused by Echinococcus. . Casoni test is an immediate (type I) hypersensitivity reaction.", 'role': 'assistant'}]