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
Not a pyrethram derivative? 
Select and explain. 
A. Cypermethrin, B. Permithrin, C. DDT, D. Resmethrin
C: DDT
Answer: C: DDT 
Explanation: park's textbook of preventive and social medicine 23rd edition *synthetic pyrethroids devoloped so far are tetramethrin,resethrin,prothrin and propahin *they are now being devoloped to replace natural pyrethrins some are found to be as much as 10ttimes as effective as naturally occuring pyrethrins .