Which Is Not an Example of Virulence as an Evolving

Which is not an example of virulence as an evolving property?

A) Cold viruses which generate more coughs and sneezes while allowing the host to remain mobile will have an evolutionary advantage over those that cause their host to be bedridden.
B) As hosts evolve more effective defenses against a given pathogen, the pathogen in turn will evolve virulence factors to combat those defenses.
C) Historically, smallpox appeared to shift from a highly virulent pathogen which killed its victims quickly to one that did not kill immediately but more easily spread from person to person.
D) The 1918 influenza pandemic primarily killed young adults rather than elderly persons which is more typical of influenza both before and after that time.
E) Each of these is an example of virulence as an evolving property.