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 Beta lactam can be used in an individual who is allergic to penicillin? 
Select and explain. 
A. Imipenem, B. Carbenicillin, C. Aztreonam, D. Ticarcillin
C: Aztreonam
Answer: C: Aztreonam 
Explanation: Aztreonam is a monobactam (contains single B-lactamase ring) and is the onlly beta lactam antibiotic that can be used in patients of penicillin hypersensitivity as cross allergy is not seen with it.