For Years, the Residents of a Small Mexican Town Complained

For years, the residents of a small Mexican town complained about large numbers of flies coming from a nearby hog farm, where millions of pigs are raised each year. In 2009, the majority of residents in this town became sick with "swine flu," caused by the H1N1 influenza virus. This virus infects people but is apparently genetically similar to a virus that infects hogs. The virus has since gone on to infect (and, in some cases, kill) people in Mexico City, has quickly spread around the entire planet, and has been declared a global pandemic. Based on this scenario and your knowledge of genetics, this virus is most likely:

A) inappropriately called the "swine flu" virus and is merely coincidentally similar to a virus that infects pigs.
B) a genetically unmodified virus that first infected pigs, then flies, then people.
C) a human virus that was transformed within the bacteria living in pig manure and can now infect pigs and humans.
D) the result of a hog-specific virus being transformed into a human-specific virus, after being carried from the hog farm to people via flying insects.
E) the first known example of a genetically modified virus that could potentially cause millions of people to die or perhaps the extinction of humans altogether.