Which of the following correctly explains why viruses are not classified with either Prokaryotic or Eukaryotic organisms?

All living organisms are divided in into prokaryotic (lacking a nucleus) and Eukaryotic cells - with a nucleus. Viruses form an exception because they are not exactly "living organisms" - they cannot live outside of their hosts (they have to live in another cell, so they are not a cell by themselves) - the answer is that they cannot live by themselves, only withing other cells (prokaryotic or eukaryotic)