This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Gynaecology & Obstetrics
Spermicidal cream which is used in contraceptives? 
Select and explain. 
A. Gossypol, B. Nonoxynol-9, C. Cent chroman, D. Clomiphene
B: Nonoxynol-9
Answer: B: Nonoxynol-9 
Explanation: Spermicidal agents provide a physical barrier to sperm penetration and a chemical spermicidal action. Active ingredient is nonoxynol-9 or octoxynol-9. Spermicides must be deposited high in the vagina in contact with the cervix sholy before intercourse. Duration of maximal effectiveness is usually no more than 1 hour. Therefore, they must be reinseed before repeat intercourse.