Fact 1: Viruses cannot reproduce by themselves.

Fact 2: Influenza viruses change continually.

Given the two facts above, answer the question "What is something that cannot reproduce by itself?" with the following options: 
- Leptospirosis
 - dangerous
 - ferns
 - fungi
 - bacteria
 - Influenza
 - acetic acid
 - anemia


 

      Influenza   