The appropriate comparison between a virus and a unicellular organism is:
Unicellular organisms have a cell membrane made from a lipid bilayer; viruses have a protein coat.
This statement accurately contrasts the structural components of unicellular organisms and viruses. Unicellular organisms, such as bacteria and protozoa, have a cellular structure with a lipid bilayer membrane, while viruses consist of genetic material encased in a protein coat (capsid) and lack a cellular structure or membrane.