The most tried medicine for the AIDS virus is [A] Zidovudine (AZT). Developed in the 1980s, AZT was one of the first antiretroviral drugs approved for HIV/AIDS treatment. It works by inhibiting the activity of the enzyme reverse transcriptase, essential for HIV replication. AZT has been a cornerstone of antiretroviral therapy (ART) regimens, helping to reduce viral load, improve immune function, and prolong the lives of individuals with HIV/AIDS. Nonoxinol-9 [C] is a spermicide, Miconazole [B] is an antifungal, and Virazole [D] is primarily used to treat respiratory syncytial virus (RSV) infections, unrelated to HIV/AIDS treatment.