Answer:
Condoms.
Step-by-step explanation:
The birth control method that also helps prevent the spread of STIs are condoms. Other birth control methods such as the birth control pill, the diaphragm, the vaginal ring, among others, do not prevent STIs and that's why they should only be used in monogamic relationships. Condoms are 98% effective protecting against many STIs such as HVI, chlamydia and gonorrea. However, there are other STIs which get transmitted by skin contact that condoms cannot prevent, such as warts, syphilis or herpes. That's why is very important to get checked regularly.