Below are the choices, the answer is no. 3:
1) The virus was descended from a common ancestor of bird, pig, and human flu viruses.
2) The infected individuals happened to be infected with all three virus types.
3)Related viruses can undergo genetic recombination if the RNA genomes mix andmatch during viral assembly.
4)The human was likely infected with various bacterial strains that contained all three<span>RNA viruses.</span>
All i know is 'hat, it is composed of three layers
