The correct 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 reflects the structural differences between unicellular organisms (which are composed of cells with membranes) and viruses (which consist of genetic material surrounded by a protein coat and lack a cell membrane).
The other options contain inaccuracies regarding energy use, reproduction, and responses to stimuli. For instance:
- Unicellular organisms do need energy to survive, whereas viruses do not have a metabolic process and rely on a host for replication.
- Viruses replicate within host cells, while unicellular organisms reproduce through various methods, including asexual reproduction.
- Both unicellular organisms and viruses can respond to stimuli, though the mechanisms may differ greatly.