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: Medicine
[{'content': 'Not useful in clostridium difficile colitis \nSelect and explain. \nA. Clindamycin, B. Metronidazole, C. Fidaxomycin, D. Fecal microbiota transplantation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Clindamycin cause C.difficile colitis.', 'role': 'assistant'}]