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: Surgery
Green coloured i.v. cannula, the size is 
Select and explain. 
A. 18, B. 20, C. 22, D. 24
A: 18
Answer: A: 18 
Explanation: Answer- A. 18Green- 18Pink- 20Blue- 22Yellow/lime- 24