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
One of the drug is beta lactamase inhibitor: 
Select and explain. 
A. Ampicillin, B. Sulbactum, C. Cloxacillin, D. Pencillin G
B: Sulbactum
Answer: B: Sulbactum 
Explanation: None