This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy: General Principles, Subject name: Pharmacology
[{'content': 'Drug of choice for antibiotic associated pseudomembranous colitis is: \nSelect and explain. \nA. Oral vancomycin, B. Metronidazole, C. Clindamycin, D. Penicillin G', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (A) Oral vancomycin(Ref: CMDT 2019/661)According to new guidelines, oral vancomycin is drug of choice for pseudomembranous colitis', 'role': 'assistant'}]