Which of the Following Is NOT True Concerning Development of an HIV

Which of the following is NOT true concerning development of an HIV vaccine or problems with one?

A) An HIV vaccine must be able to induce IgG production.
B) HIV forms, and spreads through, syncytia.
C) HIV infects many of the cells responsible for fighting infections.
D) HIV is a highly mutable virus.
E) HIV infects humans only, creating ethical and medical problems.