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
Sudha, a 20 year old female developed antibiotic associated pseudomembranous colitis caused by Clostridium difficile. Which of the following drugs is most likely to be effective in the treatment of this disease ? 
Select and explain. 
A. Ampicillin, B. Clindamycin, C. Metronidazole, D. Chloramphenicol
C: Metronidazole
Answer: C: Metronidazole 
Explanation: None