AIDS Cause: Identifying the Pathogen

The question requires identifying the type of pathogen responsible for causing AIDS (Acquired Immunodeficiency Syndrome).

Analysis of Options:

• Protozoa: These are single-celled eukaryotic organisms and are not the cause of AIDS.
• Virus: AIDS is caused by the Human Immunodeficiency Virus (HIV). This is the correct classification for the pathogen.
• Helminths: These are parasitic worms and do not cause AIDS.
• Bacteria: These are single-celled prokaryotic microorganisms and are not the cause of AIDS.

HIV is a retrovirus that attacks the immune system. Therefore, the correct answer is Virus.