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': 'Casoni test is positive in: \nSelect and explain. \nA. Diphtheria, B. Scarlet fever, C. Echinococcus, D. Kala Azar', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Echinococcus', 'role': 'assistant'}]