Evidence Suggests That Factors Which Contribute Towards the Virulence of E.coli

Evidence suggests that factors which contribute towards the virulence of E.coli strain O157:H7,a bacterial strain reported to cause 2,100 hospitalizations in the US annually,are caused by genes from a virus that infects bacteria.Considering this evidence,which statement most likely explains how the O157:H7 population acquired the genetic variation that distinguishes the strain from harmless E.coli strains,such as those that reside in our intestines?

A) The virus entered the bacterial cell allowing the bacteria's cellular machinery to create new viruses.
B) Viral envelope proteins bind to receptors on the bacterial membrane, allowing the viral genetic material to enter the bacterium and become translated into proteins.
C) The virus entered the cell and acquired specific genes from the bacteria to increase the virulence of the virus.
D) The virus infected the bacterium, and allowed the bacterial population to replicate with a copy of the phage genome in each new bacterium.
E) The virus entered the cell and resulted in mutation of bacterial genes.