This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contraception, Subject name: Gynaecology & Obstetrics
[{'content': 'Which of the following statements is true regarding spermicides found in vaginal foams, creams, and suppositories? \nSelect and explain. \nA. The active agent in these spermicides is nonoxynol-9, B. The active agent in these spermicides is levonorgestrel, C. Effectiveness is higher in younger users, D. Effectiveness is higher than that of the diaphragm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: All spermicides contain an ingredient, usually nonoxynol-9, that immobilizes or kills sperm on contact. Spermicides provide a mechanical barrier and need to be placed into the vagina before each coital act. Their effectiveness increases with increasing age of the women who use them, probably due to increased motivation. The effectiveness of spermicides is similar to that of the diaphragm, and increases with the concomitant use of condoms. Although it has been repoed that contraceptive failures with spermicides may be associated with an increased incidence of congenital malformations, this finding has not been confirmed in several large studies and is not believed to be valid. Levonorgestrel is a synthetic progestational agent found in several combination oral contraceptive pills.', 'role': 'assistant'}]