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: Social & Preventive Medicine
[{'content': 'Man in the only host for \nSelect and explain. \nA. Dracunculus medinensis, B. Trichuris trichura, C. Onchocerca volvolus, D. Wuchereria bancrofti', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Obligate Host: Means the only host\n– Man in Measles\n– Man in Typhoid', 'role': 'assistant'}]