Hint:It is difficult to identify viruses as live or non-living species. These viruses are inactive when outside host cells, but are active in host cells. They are called living as well as non-living.
Complete answer:An infectious virus is a non-cellular entity composed of genetic and protein, which can only enter and replicate within living cells of bacteria, plants, and animal species. Scientists identify viruses as neither alive nor non-living. The viruses are the main characteristics of living organisms and nonliving entities.
This is because both the living and non-living viruses are characteristic. Viruses can replicate inside a host as in any other living organism, for example, but when the virus lies beyond the host cell the capacity to reproduce is lost. The explanation is that the viruses do not have cellular machinery to replicate, and so they are catching a living cell. Viruses also can crystallize that no other living organisms can do. There are factors that contribute to the classification of viruses in the grey – from living to non-living.
A virus is a small infectious agent that only replicates with cellular machinery in the live cells of other organisms. Viruses infect every kind of life form, including bacteria and archaea, from animals and plants through to microorganisms. A cell or cellular machinery environment often includes the replication of isolated chromosomes.
Option D- Require the environment of a cell to replicate is therefore right.
Note: As a genetic variable and nucleic acid with single or double strands, many viruses have either DNA or RNA. Both infectious viruses have a nucleic acid and an external protein shell called a virion. In 1897, Martinus Willem Beijerinck, a Netherlands microbiologist, gave the word virus. It comes from Latin, meaning poison or toxic substance. Virology is the study of viruses.