What contraceptive method is effective in preventing the transmission of STIs?

Condoms are the only contraceptive method among the options provided that effectively prevent the transmission of sexually transmitted infections (STIs). They work as a barrier during sexual intercourse, blocking the exchange of bodily fluids, which is a common route for STI transmission. Additionally, condoms help reduce the risk of infections such as HIV, gonorrhea, and chlamydia, making them a crucial option for individuals who are sexually active and concerned about STIs.

In contrast, birth control pills primarily prevent pregnancy by inhibiting ovulation and do not provide any protection against STIs. IUDs (intrauterine devices) are a highly effective form of contraception, but they also do not offer any protection against infections. Emergency contraception is designed to prevent pregnancy after unprotected intercourse, but similarly to the other methods mentioned, it does not guard against STIs. Therefore, when considering both pregnancy prevention and STI protection, condoms are the most effective choice.