Final answer:
HIV binds to the CD4 receptor on the host cell, which is a glycoprotein on the surfaces of T cells. The interaction between HIV's envelope glycoprotein gp120 and the CD4 receptor is key to the virus's ability to infect the cell and is a target for drug development.
Step-by-step explanation:
HIV, the virus that causes AIDS, exploits specific receptors on the surface of certain immune cells to gain entry into them. The correct answer to which receptor HIV binds is C. CD4. The CD4 receptor is a glycoprotein found predominantly on the surfaces of T cells, which are a critical part of the immune system. HIV's envelope glycoprotein, gp120, specifically interacts with the CD4 receptor to attach to and eventually enter the host cell. The viral and host cell membranes fuse, allowing the viral contents to enter and begin the process of integration and replication. Understanding this interaction is crucial, as it is a target for anti-HIV drug development.