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: Medicine
[{'content': 'Main Vector in urban malaria \nSelect and explain. \nA. A. Culicifacies, B. A. Stephensi, C. A. Fluviatilis, D. A. Epiroticus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A. Culicifacies - Main vector in rural areas.\nA. Stephensi - Main vector in urban areas.', 'role': 'assistant'}]