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 are first generation cephalosporins except : 
Select and explain. 
A. Cefadroxil, B. Cefazolin, C. Cephalexin, D. Cefaclor
D: Cefaclor
Answer: D: Cefaclor 
Explanation: None