This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical Entomology, Subject name: Social & Preventive Medicine
[{'content': 'All are true about DDT except \nSelect and explain. \nA. Kills mosquito immediately, B. Insecticidal propeies discovered by Paul H. Muller, C. Residual action lasts for 18 months, D. Contact/ nerve poison', 'role': 'user'}, {'content': 'Answer: A \nExplanation: DDT takes several hours to kill mosquito Dichloro Diphenyl trichloroethan (DDT) First synthesis by - ZIEDLER Propeies by - Paul muller (Nobel Prize) No repellant action Takes several hours to kill Residual action lasts for 18 months Most active form of DDT - PARA - PARA ISOMER Mode of action - At as a contact/Nerve poison - Inhibits Acetylcholinesterase', 'role': 'assistant'}]