Which Is More Dangerous to Human Beings: Antigenic DRIFT or Antigenic

Which is more dangerous to human beings: antigenic DRIFT or antigenic SHIFT?

A) Antigenic DRIFT, since this produces the quickest and largest degree of changes in the virus structure  and we may not have immunity against it.
B) Antigenic SHIFT, since this produces the quickest and largest degree of changes in the virus structure and we may not have immunity against it.
C) Antigenic DRIFT; the small changes make the virus look like something we already have an immune response in place for, but we actually don't, letting the virus hide from the immune responses for a longer period of time.
D) Antigenic SHIFT; the process completely changes the virus, allowing it to jump from one species to another (such as from birds into humans) . As such, we have no responses in place for the new virus.
E) These are equally dangerous. In both cases, major genetic and phenotypic changes occur in the virus, which means that people have absolutely no immune responses in place for dealing with the infection.