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: Microbiology
All are used for anaerobic streptococci except - 
Select and explain. 
A. Penicillin, B. Carbenicillin, C. Clindamycin, D. Vancomycin
B: Carbenicillin
Answer: B: Carbenicillin 
Explanation: None