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': 'The essential ingredient in the space sprays for vector control is - \nSelect and explain. \nA. Malathion, B. Fenithion, C. Fenithion, D. BHC', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Residual insecticides: new equipment has been developed for ULV space spraying.The most extensively used insecticides are malathion and fenitrothion for ULV fogging (refer pgno:773 park 23 rd edition)', 'role': 'assistant'}]