You are presented with the question "what is so small it can only be seen with an electron microscope?" and the following answer choices: 
- clouds
 - cell
 - DNA
 - ovum
 - HIV
 - magnified
 - h2o
 - RNA

Now knowing that viruses are so small that they can be seen only with an electron microscope and where most viruses are DNA, HIV is an RNA virus, choose the best answer.


 

     HIV    