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 antibiotics is most frequently associated with pseudomembranous colitis? 
Select and explain. 
A. Ampicillin, B. Penicillin, C. Clindamycin, D. Cephalosporin
C: Clindamycin
Answer: C: Clindamycin 
Explanation: None