Final answer:
A Copper IUD interferes with sperm mobility and prevents implantation but does not protect against STIs. A diaphragm acts as a barrier to sperm but increases the risk of urinary tract infections. Sterilization via tubal ligation or vasectomy is highly effective but is typically irreversible.
Step-by-step explanation:
Understanding Contraceptive Methods
A chemical that works by inhibiting sperm function, is effective against HIV and other STIs, and is not harmful to the vaginal or cervical cells is not explicitly listed among the options provided, which include Nonoxynol-9, Levonorgestrel, Copper IUD, and Diaphragm. However, when evaluating the effectiveness of contraception methods, the Intrauterine device (IUD) is considered highly effective and reversible. In particular, the Copper IUD interferes with sperm mobility and prevents implantation, while the hormonal IUD releases progestin which thickens the cervical mucus and prevents ovulation. However, for protection against STIs, barrier methods like condoms are necessary as most IUDs do not offer this protection.
A diaphragm is a barrier method type of contraception placed over the cervix to block sperm from entering the uterus. It's typically used with spermicide and needs to be inserted before sexual intercourse. While diaphragms can help prevent pregnancy, they do not provide protection against STIs and can increase the risk of urinary tract infections.
Tubal ligation and vasectomy are forms of sterilization, which are the most effective methods of contraception but usually irreversible. An IUD can also be used as emergency contraception if inserted within five days after unprotected intercourse.