This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Airway, Subject name: Anaesthesia
What is Laser tubes- 
Select and explain. 
A. It is tube made up of PVC wrapped in two layers, one metallic and other non - reflective layer, B. It is tube made up of red rubber, C. It is a metallic tube to prevent any airway fire, D. It is tube made up of laser resistant material
A: It is tube made up of PVC wrapped in two layers, one metallic and other non - reflective layer
Answer: A: It is tube made up of PVC wrapped in two layers, one metallic and other non - reflective layer 
Explanation: Like standard endotracheal tubes, laser tubes are made of polyvinylchloride (PVC), which is flammable in the presence of oxygen and an ignition source, i.e. laser light.The PVC core of the laser tubes is therefore wrapped in two layers, one metallic foil layer which protects the actual tube from the laser light, and an outer non-reflective layer. It is used for Laser surgery.