Answer: The correct answer is- Viruses can not reproduce by their own.
Viruses are non cellular, microscopic, infectious, non living agents, primarily composed of nucleic acid ( which could be DNA or RNA) that is surrounded by a coat of protein called capsid. They are not composed of cell and can not produce energy by themselves.
They lack a machinery for replicating their genetic material and therefore require a body of specific host ( such as bacteria) where they can replicate their genome and produce more viral copies.
Thus, scientist do not include virus while classifying living things.