This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacokinetics, Subject name: Pharmacology
[{'content': 'Oral contraceptive failure occurs by intake of: \nSelect and explain. \nA. Rifampicin, B. Penicillin, C. Chloroquine, D. Metronidazole', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' Rifampicin Rifampicin is an enzyme inducer. It induces the metabolism of oral contraceptives and reduce cone, of OCP's in the body.", 'role': 'assistant'}]