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: Gynaecology & Obstetrics
[{'content': 'Contraceptive methods with failure rate <5:a) Copper - Tb) Vaginal spongec) Condomd) OCPe) Tubectomy \nSelect and explain. \nA. acd, B. bde, C. ade, D. ad', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]