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
A company executive, who travels worldwide, present with upper abdominal mass and +ve Casoni's test. The organism is: 
Select and explain. 
A. Echinococcus, B. E. histolytica, C. Hepatitis, D. Ascariasis
A: Echinococcus
Answer: A: Echinococcus 
Explanation: Ans. is 'a' i.e., EchinococcusCasoni's test: This is an immediate hypersensitivity (Type I) skin test used for diagnosis of hydatid disease.