What are sexually transmitted infections (STIs) or venereal diseases (VDs)?

Sexually transmitted infections (STIs), also known as venereal diseases (VDs), are primarily defined as illnesses that are transmitted through sexual behavior, including vaginal, anal, and oral intercourse. These infections can be caused by a variety of pathogens such as bacteria, viruses, and parasites, and they are spread through sexual contact with an infected person. This definition underscores the importance of understanding the routes of transmission and the various forms of sexual activity that can facilitate the spread of these infections.

While other options mention conditions related to hygiene or reproductive organs, they do not capture the essential characteristic of STIs as being transmitted through sexual activities. Moreover, not all infectious diseases fall under the category of STIs, which further clarifies why the correct answer focuses specifically on the sexual transmission aspect.