Which method of contraception can be categorized as a barrier method?

A barrier method of contraception works by preventing sperm from reaching the egg, thus reducing the likelihood of fertilization. The cap or diaphragm specifically fits this description as it is designed to cover the cervix, acting as a physical barrier to sperm.

In contrast, the intrauterine device (IUD) is classified as a long-term hormonal or non-hormonal method that maintains its effectiveness by altering the environment within the uterus. The combined pill is a hormonal method that works primarily by preventing ovulation and altering the uterine lining. Lastly, the emergency contraceptive pill is designed to prevent pregnancy after unprotected intercourse but operates through hormonal means rather than through a barrier. Hence, the cap or diaphragm is distinctly recognized as a barrier method among these options.