Which of the following statements best reflects what we know about how influenza virus moves between host species? A.
An influenza virus fuses with a different type of virus (like HSV) and gains new DNA which enable the new virus to be transmitted to a wider variety of host species.

B.
In an animal, such as a pig, the influenza virus is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected.

C.
An influenza virus from a human epidemic or pandemic infects birds; the birds replicate mutant versions of that virus and then pass the new forms back to humans.

D.
An animal, such as a pig, is infected with more than one strain of the influenza virus and the genomes reassort into new combinations that can facilitate spread to other species.