* Please choose BEST answer*?

I would say D. Viruses are not living organisms like a unicellular organism so they won't have the ability to metabolize things. There are usually two types of viruses from what I know, one that have a cell membrane envelope, like adenoviruses and another that contains a protein coat called a capsid. Either case, they contain protein and either DNA or RNA. Once they infect their host, they introduce these elements which helps it to either integrate their genome into the host or reproduce to make more viruses. In a nutshell this is what is common between a cell and virus.