Identify, which is not the sexually transmitted infection?

Rheumatoid arthritis

The correct answer is Option (3) → Rheumatoid arthritis 

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. Among these, HIV infection is most dangerous. Except for hepatitis-B, genital herpes and HIV infections, other diseases are completely curable if detected early and treated properly. Some of these infections like hepatitis–B and HIV can also be transmitted by sharing of injection needles, surgical instruments, etc., with infected persons, transfusion of blood, or from an infected mother to the foetus too. Shaking hands with an infected person does not involve contact with blood or other body fluids, so it is not a means of transmission for STIs.

Rheumatoid arthritis is an example of an autoimmune disease. It is a chronic inflammatory disorder that primarily affects the joints, causing pain, swelling, stiffness, and in some cases, joint deformity. In rheumatoid arthritis, the immune system mistakenly attacks the body's own tissues, particularly the the lining of the joints, leading to joint inflammation and damage.