A Soluble Form of the CD4 Protein Was Once Investigated

A soluble form of the CD4 protein was once investigated as a treatment for HIV infection.How would this protein work to block infection.

A) It would raise the pH of the endosome and prevent activation of the fusion protein.
B) It would bind to the cell membrane and prevent fusion of the HIV virion with the plasma membrane.
C) It would interact with the host cell receptor and prevent binding by the virion glycoproetin.
D) It would interact with the HIV envelope glycoprotein and block its interaction with the host cell receptor.
E) It would inhibit entry of the viral genome into the cell nucleus.