This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Pharmacology
Colour of nitrous oxide cylinder is? 
Select and explain. 
A. Blue, B. Blue body with white shoulder, C. White, D. Black
A: Blue
Answer: A: Blue 
Explanation: N2O (blue) Cyclopropane (orange) Oxygen (black & white) Entonox (blue & white)