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: Pharmacology
Which of the following opioid analgesic is suitable for haemodynamically unstable patients ? 
Select and explain. 
A. Morphine, B. Meperidine, C. Fentanyl, D. Pentazocine
C: Fentanyl
Answer: C: Fentanyl 
Explanation: None