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
Contraceptive methods with failure rate <5:a) Copper - Tb) Vaginal spongec) Condomd) OCPe) Tubectomy 
Select and explain. 
A. acd, B. bde, C. ade, D. ad
C: ade
Answer: C: ade 
Explanation: None