You are presented with the question "what often infects bacteria?" and the following answer choices: 
- major threat to health
 - h2o
 - simplest known organisms
 - Food poisoning
 - mercury
 - humans
 - By wind and rain
 - microorganisms

Now knowing that viruses often infect bacteria and viruses Viruses are the simplest organisms known, choose the best answer.


 

   simplest known organisms      