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: Anaesthesia
Pin code index of N2O is – 
Select and explain. 
A. 1,6, B. 2,5, C. 2,6, D. 3,5
D: 3,5
Answer: D: 3,5 
Explanation: None