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
All of the following are beta lactamase inhibitors except : 
Select and explain. 
A. Clavulanic acid, B. Sulbactam, C. Tazobactam, D. Aztreonam
D: Aztreonam
Answer: D: Aztreonam 
Explanation: None