Developing an AIDS Vaccine Is Not Impossible, as Some Skeptics

Multiple Choice

Developing an AIDS vaccine is not impossible, as some skeptics claim. Research suggests that the human immune system is better at fighting HIV than was originally thought. Most of those infected suppress the virus for years without developing AIDS. A small number never contract the virus despite repeated exposures. If we can figure out the mechanism that accounts for this, we'll have clues about how to engineer a vaccine. Seth Berkley, "Don't Quit on an AIDS Vaccine"

A) Argument; conclusion: If we can figure out the mechanism ... engineer a vaccine.
B) Nonargument.
C) Argument; conclusion: Most of those infected ... without developing AIDS.
D) Argument; conclusion: Research suggests ... than was originally thought.
E) Argument; conclusion: Developing an AIDS vaccine ... skeptics claim.