a) HIV (Human Immunodeficiency Virus) is a virus that attacks the body's immune system, specifically CD4 cells (T cells), which help the body fight off infections. AIDS (Acquired Immunodeficiency Syndrome) is the most advanced stage of HIV infection. It occurs when the immune system is severely damaged by the virus, leading to a high susceptibility to opportunistic infections and certain cancers. The key difference is that HIV is the virus itself, while AIDS is the syndrome (a collection of symptoms and infections) that results from long-term, untreated HIV infection. Send me the next one 📸