Which of the Following Statements Best Describes the Effort to Find

Multiple Choice

Which of the following statements best describes the effort to find a vaccine against HIV?

A) It is impossible to develop a vaccine against HIV owing to its ability to undergo slow mutation.
B) There has been considerable research, but no clinical trials have been conducted.
C) There have been several clinical trials, but all were declared failures.
D) It has already been developed using HIV-specific antibodies.