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
The following is not a Nerve gas ? 
Select and explain. 
A. Sarin, B. Tabun, C. Soman, D. Pyrolan
D: Pyrolan
Answer: D: Pyrolan 
Explanation: Ans. is 'd' i.e., Pyrolan Nerve gases are a class of organophosphates that act by inhibiting enzyme acetylcholinesteraze, an enzyme that destroys acetylcholine. The classical examples are tabun, sarin, soman and cyclosarin. These are used as chemical weapons in wars, i.e. chemical warfare.