What Critical Role Is Often Played by Pigs in the Epidemiology

What critical role is often played by pigs in the epidemiology of influenza virus?

A) Pigs are the reservoir for influenza virus and most humans become infected by contact with respiratory secretions of pigs.
B) Pigs are the reservoir for influenza viruses and disease can be transmitted to humans by consuming undercooked pork.
C) Pigs can become infected simultaneously with both human,avian,and swine varieties of influenza viruses,providing an opportunity for genetic recombination resulting in antigenic drift.
D) Pigs harbor influenza viruses that are much more virulent than avian strains and human strains.