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: Psychiatry
The most common postoperative psychiatric condition is: 
Select and explain. 
A. Schizophrenia, B. Delirium, C. Chronic brain syndrome, D. Depression
B: Delirium
Answer: B: Delirium 
Explanation: Delirium