Which among the following is caused by retrovirus ?

AIDS

The correct answer is Option (1) -AIDS

Among the options provided, AIDS (Acquired Immunodeficiency Syndrome) is caused by a retrovirus. The retrovirus responsible for AIDS is the Human Immunodeficiency Virus (HIV). Syphilis, gonorrhea, and trichomoniasis are caused by bacteria (Treponema pallidum for syphilis, Neisseria gonorrhoeae for gonorrhea, and Trichomonas vaginalis for trichomoniasis), not retroviruses.