Which of the following contraceptive methods provides protection against sexually transmitted infections (STIs) in addition to preventing pregnancy?

Choice A rationale The Intrauterine device (IUD) is a highly effective, long-acting reversible contraceptive that prevents pregnancy primarily by preventing fertilization or implantation, possibly by causing a local sterile inflammatory response. However, it offers no physical barrier and provides absolutely no protection against the transmission of sexually transmitted infections (STIs) since it resides within the uterus. Choice B rationale The male condom is a thin sheath, usually made of latex or polyurethane, that acts as a physical barrier, preventing the exchange of bodily fluids and direct skin-to-skin contact between genital areas. This dual function makes it the only widely available method that is effective at reducing the risk of both pregnancy and most sexually transmitted infections (STIs). Choice C rationale The vaginal ring releases synthetic hormones (estrogen and progestin) that prevent ovulation, thus preventing pregnancy. Like oral contraceptive pills, it works systemically and provides no physical barrier against the microorganisms that cause sexually transmitted infections. Therefore, it does not offer protection against STIs. Choice D rationale Oral contraceptive pills contain synthetic hormones (estrogen and progestin) that primarily inhibit ovulation, making the chance of pregnancy extremely low. However, they work systemically and provide no mechanical barrier against the transmission of pathogens, thus offering no protection against sexually transmitted infections (STIs).