What progressive disease is caused by the immunodeficiency virus and can lead to a significantly lowered life expectancy if untreated?

The correct answer is AIDS. Acquired Immunodeficiency Syndrome (AIDS) is the condition that results from the progression of the Human Immunodeficiency Virus (HIV) infection. When a person is infected with HIV, the virus attacks and weakens the immune system, specifically targeting CD4 cells, which are crucial for immune function. If left untreated, the infection can lead to AIDS, where the immune system becomes severely compromised, making the individual vulnerable to opportunistic infections and certain cancers.

AIDS is characterized by a significant decline in the immune response, and if not managed, it can lead to a markedly reduced life expectancy. Treatment with antiretroviral therapy can help control the virus, maintain the immune system, and potentially lead to a near-normal lifespan for those living with HIV, but without treatment, the progression to AIDS is dangerous and often fatal.

While HIV is the virus itself, AIDS is the advanced stage of that infection. Other options, such as herpes or syphilis, are different types of sexually transmitted infections that do not cause the same immunodeficiency effects as HIV/AIDS and are not related to the same progressive disease model.