Evidence suggests that factors contributing to the virulence of E. coli strain O157:H7, a bacterial strain associated with food poisoning deaths, 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 residing in our intestines?

A. Viral envelope proteins bind to receptors on the bacterial membrane, allowing the viral genetic material to enter the bacterium and become translated into proteins.

B. The virus infected the bacterium, allowing the bacterial population to replicate with a copy of the phage genome in each new bacterium.

C. The virus entered the bacterial cell and incorporated its DNA into the bacterial genome, allowing the bacteria's cellular machinery to create new viruses.

D. The virus entered the cell and acquired specific genes from the bacteria to increase the virulence of the virus.