Fact 1: Viruses often infect bacteria.

Fact 2: Infected birds spread the bacteria in their droppings.

Given the two facts above, answer the question "Viruses often can spread bacteria through what?" with the following options: 
- the skin
 - microscopes
 - contamination
 - covering
 - washing
 - alveoli
 - droppings
 - coating


 

       droppings  