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: Anaesthesia
Cause of post operative hypeension 
Select and explain. 
A. Pre-operative hypeension, B. Inadequate analgesia, C. Phaeochromocytoma, D. All
D: All
Answer: D: All 
Explanation: All i.e. A, B, C