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 antibacterial agents acts by inhibiting cell wall synthesis except: 
Select and explain. 
A. Carbapenems, B. Monobactams, C. Cephamycins, D. Nitrofurantoin
D: Nitrofurantoin
Answer: D: Nitrofurantoin 
Explanation: None