What is the contraceptive sponge designed to do?

The contraceptive sponge is designed to kill sperm, thereby preventing fertilization and acting as a barrier method of contraception. The sponge is made from a soft, flexible material and contains spermicide, which is a chemical agent that immobilizes and destroys sperm before they can reach an egg. When inserted into the vagina, it covers the cervix and releases the spermicide over time, increasing its effectiveness. This method is intended specifically for contraception, making it an option for individuals seeking to prevent pregnancy.

In contrast, other options do not pertain to the primary function of the sponge. Preventing STIs is not a function of the sponge, as it does not provide a barrier against sexually transmitted infections. Regulating menstrual cycles or enhancing fertility are unrelated to the purpose of the sponge, which solely focuses on preventing sperm from entering the uterus. Therefore, the correct answer accurately reflects the sponge's designed purpose in contraceptive use.