Choice A rationale:

This choice describes viral STIs, which are caused by viruses infecting body cells. While antiviral drugs can manage these infections, they cannot be completely cured. Examples of viral STIs include HIV and genital warts.

Choice B rationale:

Protozoal STIs are indeed caused by protozoa infecting the genital tract. They can be effectively treated with antiprotozoal drugs, and if left untreated, they may lead to various symptoms such as vaginitis, cervicitis, urethritis, or prostatitis. Trichomoniasis is an example of a protozoal STI.

Choice C rationale:

This option refers to bacterial STIs, not protozoal ones. Bacterial STIs can be cured with antibiotics and may cause complications such as pelvic inflammatory disease, infertility, ectopic pregnancy, or congenital syphilis if left untreated. Examples include chlamydia, gonorrhea, and syphilis.

Choice D rationale:

This describes parasitic STIs caused by mites or insects infesting the genital skin or hair. These infections can be treated with topical agents or oral drugs. Examples include pubic lice (crabs) and scabies.