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
[{'content': 'One of the following drug is NOT effective against anaerobes - \nSelect and explain. \nA. Penicillin, B. Chloramphenicol, C. Gentamicin, D. Clindamycin', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Gentamicin", 'role': 'assistant'}]