The HIV protease has been the target of several anti- HIV medications. This antiviral strategy is possible because

A) the HIV protease is easily precipitated out of the cell by combining with certain salt solutions.
B) the HIV protease cleaves at specific places in viral polypeptides, which results in the formation of active viral proteins.
C) these drugs are very specific to the active site of the HIV protease.
D) both A and B apply.
E) both B and C apply.