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: Surgery
[{'content': 'In occult filariasis, all are true except \nSelect and explain. \nA. Microfilaria is demonstrable in blood, B. Microfilaria is demonstrable in lungs, C. Eosinophilia present, D. Thrombophlebitis can occur', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In occult filariasis, microfilaria is not demonstrable in blood.', 'role': 'assistant'}]