This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'Most efficient larval control method to prevent transmission of urban malaria - \nSelect and explain. \nA. Covering overhead tanks, B. Cleaning of drains, C. Filling of ditches and cesspools, D. Uprooting of plants', 'role': 'user'}, {'content': "Answer: A \nExplanation: Vector of malaria in urban areas breeds largely in man-made containers including overhead tanks and underground water storage tanks, water coolers, cisterns, roof gutters, flower vases, bottles, ornamental ponds.etc which can collect water control of urban malaria lies in the use of larvivorous fish and larvicides in waterbodies. The breeding habitat of Anopheles is clean water. In the given options Overhead tank is the only Anopheles breeding place and hence it should be the most effective method to prevent transmission. Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 830.", 'role': 'assistant'}]