Which of the Following Is the Most Important Reason That

Multiple Choice

Which of the following is the most important reason that developing treatments and vaccines,as well as staging an effective immune response for HIV infections,has been so difficult compared with other viruses?

A) The virus evades the immune system and drugs by hiding inside cells of the immune system,such as helper T cells.
B) The virus has few,if any,replication-correcting enzymes,and consequently mutates at a high rate.
C) The virus has no recognizable antigens and,thus,cannot be identified easily by the host's immune system.
D) Researchers probably have not yet identified the actual cause of AIDS and,thus,cannot target their drug development accordingly.