You are presented with the question "germs that cause people to get sick cannot reproduce by what?" and the following answer choices: 
- anemia
 - dry conditions
 - harm them
 - contamination
 - burning coal
 - Smoking
 - heat or cold
 - themselves

Now knowing that viruses cannot reproduce by themselves and viruses are germs that cause people to get sick, choose the best answer.


 

        themselves 