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
Ratio of O2 : N2O in Entonox is – 
Select and explain. 
A. 50:50:00, B. 60:40:00, C. 40 : 60, D. 25 : 75
A: 50:50:00
Answer: A: 50:50:00 
Explanation: Entonox contain equal amount (50/50) of N2O and O2.