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
Under Insecticide Treated Bed N ets Program me, insecticide used is 
Select and explain. 
A. Deltamethrin, B. Malathion, C. Lindone, D. Fenitrothion
A: Deltamethrin
Answer: A: Deltamethrin 
Explanation: Inseccide Treated Bed Nets (ITBN) Programme (esp. deltamethrin) has resulted in significant decline in malaria incidence and API Average decline in anopheline mosquito density - 68% Average decline in cuicine mosquito density - 50%
Chemicals used in ITBN Programme : Synthec pyretheroids Deltamethrin : 2.5% in dosage of 25 mg/m2 Cyfluthrin: 5% in dosage of 50 mg/m2 Other inseccides used : Permethrin, Lambdacyhalothrin, Etofenprox, Cypermethrin
Effecveness of pyrethroids: For 6-12 months (Retreatment every 6 months)
Long-lasng inseccidal mosquito nets (LLINs) :

Also use pyrethroid inseccides, and a chemical binder that allows the nets to be washed > 20 mes, allowing use for > 3 years.