Which one of the following medication classes prevents HIV from binding to and entering CD4 cells?

The correct choice focuses on fusion inhibitors, which specifically target the process by which HIV binds to and enters CD4 cells. These medications work by interfering with the viral fusion process—this is when the virus merges with the host cell's membrane, a critical step that allows HIV to gain entry into CD4 cells, which are essential for the immune response.

By inhibiting this fusion process, fusion inhibitors prevent the virus from uncoating and releasing its genetic material into the host cell, effectively blocking the infection cycle at an early stage. This is crucial in the treatment and management of HIV, as it directly impacts the virus's ability to replicate and spread within the body.

The other medication classes serve different roles in HIV treatment. Protease inhibitors, for instance, work by preventing the viral protease enzyme from processing viral proteins necessary for the maturation of infectious viral particles, while nucleoside reverse transcriptase inhibitors interrupt the reverse transcription of viral RNA into DNA. CCR5 antagonists, on the other hand, block the CCR5 co-receptor on CD4 cells, preventing HIV from utilizing this entry pathway. Each of these strategies is important in the overall management of HIV, but fusion inhibitors are specifically designed to stop the virus from binding to and entering the cells