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 is not an acetic acid derivative? 
Select and explain. 
A. Ketorolac, B. Ketoprofen, C. Indomethacin, D. Nabumetone
B: Ketoprofen
Answer: B: Ketoprofen 
Explanation: None