Fact 1: Viruses cause many human diseases.

Fact 2: Bacterial contamination can spread diseases to humans and livestock.

Given the two facts above, answer the question "Viruses cause contamination spreading what?" with the following options: 
- alleles
 - Toxicity
 - Pollution
 - food
 - diseases
 - cells
 - pores
 - microbes


 

     diseases    