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 30-year old patient presented with features of acute meningoencephalitis in the casualty. His CSF on wet mount microscopy revealed motile unicellular microorganisms. The most likely organism is - \nSelect and explain. \nA. Naegleria fowleri, B. Acanthamoeba castellani, C. Entamoeba histolytica, D. Trypanosoma cruzi', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Provided history of acute meningoencephalitis with demonstration of motile trophozoites in CSF wet mount suggests\xa0diagnosis of N.fowleri.\nEventhough Acanthamoeba also causes meningoencephalitis, it is not acute in nature and it occurs mainly in\xa0immunocompromised host.', 'role': 'assistant'}]