You are presented with the quiz "What are not cells at all, so they are neither prokaryotes nor eukaryotes?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "viruses are not cells at all, so they are neither prokaryotes nor eukaryotes" and "viruses Viruses are the smallest agents of disease". 

So, what's the best answer to the question?


 

   The smallest agent of disease        