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
The most common anesthetic complication occurring within first 24 hours after surgery under general anesthetics is: 
Select and explain. 
A. Hypertension, B. Renal failure, C. Atelectasis, D. Cardiac arrest
C: Atelectasis
Answer: C: Atelectasis 
Explanation: None