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
Commonest aery for cannulation is - 
Select and explain. 
A. Radial, B. Ulnar, C. Brachial, D. Cubital
A: Radial
Answer: A: Radial 
Explanation: Answer is 'a' i.e. Radial "Aerial puncture and cannulation is performed to measure the Pa02, PaCO2, Sa02 and pH to clarify the acid-base and electrolyte status. Any aery that can be compressed after puncture may be used (but not end-aeries); usually the radial (preferred), brachial, or femoral" - Lee 12/e