This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parasitology, Subject name: Microbiology
[{'content': "A company executive, who travels worldwide, present with upper abdominal mass and +ve Casoni's test. The organism is: \nSelect and explain. \nA. Echinococcus, B. E. histolytica, C. Hepatitis, D. Ascariasis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., EchinococcusCasoni's test: This is an immediate hypersensitivity (Type I) skin test used for diagnosis of hydatid disease.", 'role': 'assistant'}]