Which of the following mechanism prevents fitting of wrong gas cylinder to the anaesthesia machine in operation theatre? (Repeat)

Ans: A (Pin index system) Ref: Miller Textbook of Anaesthesia. 6th edition Explanation:The Pin Index Safety System, or PISS, is a safety system that uses geometric features on the yoke to ensure that pneumatic connections between a gas cylinder and a machine that uses pressurized gases are not connected to the wrong gas yoke.This system can be seen on an anesthesia machine.Each gas cylinder has a pin configuration to fit its respective gas yoke.PIN Index of Commonly Used Gases in AnesthesiaO2: 2-5N2O: 3-5Air: 1-5CO2: 1-6Heliox: 2-4 Entonox: 7