This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anaesthetic equipments, Subject name: Anaesthesia
What is the pressure at which oxygen is stored ? 
Select and explain. 
A. 75 psi, B. 1600 psi, C. 760 psi, D. 2200 psi
D: 2200 psi
Answer: D: 2200 psi 
Explanation: Oxygen is stored at a pressure of 1900psi