Fact 1: Viruses often infect bacteria.

Fact 2: Bacteria are normally classified as either 'good' bacteria or 'bad' bacteria.

Given the two facts above, answer the question "How many types can viruses infect?" with the following options: 
- mice
 - pigs
 - bird
 - RNA
 - ova
 - tiny
 - HPV
 - Two


 

        Two 