Which of the following is not a sexually transmitted infection (STI)?

The correct answer is Option (2) → Cancer

Sexually transmitted infections (STIs) are infections passed from one person to another through sexual intercourse. They are caused by microbes such as bacteria and viruses. A disease that is not caused by a microbe passed on in this way is not an STI.

Option (1) Gonorrhoea — A sexually transmitted infection. Gonorrhoea spreads through sexual contact. Like most STIs, it can be cured if it is detected early and treated properly.

Option (2) Cancer — Not a sexually transmitted infection. Cancer starts when the body’s own cells divide without control and form tumours. It is not caught from another person through sexual contact.

Option (3) Hepatitis-B — A sexually transmitted infection. Hepatitis-B is a viral infection that spreads through sexual contact, and also through shared needles and transfusion of blood. It is one of the STIs that cannot be completely cured.

Option (4) Chlamydiasis — A sexually transmitted infection. Chlamydiasis is an infection of the reproductive tract passed on through sexual contact.

NCERT Extract:
Sexually Transmitted Infections (STIs) – “Infections or diseases which are transmitted through sexual intercourse are collectively called sexually transmitted infections (STI) or venereal diseases (VD) or reproductive tract infections (RTI). Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, trichomoniasis, hepatitis-B and of course, the most discussed infection in the recent years, HIV leading to AIDS are some of the common STIs.”
Cancer – “Cancer is one of the most dreaded diseases of human beings and is a major cause of death all over the globe. … In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of these regulatory mechanisms.”