Viruses are not considered organisms because they don't have cell membranes, organelles, and do not carry out vital life functions, although they do have a form of DNA (or similar RNA). A researcher proposing to categorize viruses in the tree of life would need to:
A) apply his/her proposal to any newly discovered virus, since others aren't currently considered organisms.
B) establish any virus as a control group for experimentation with established domains of organisms.
C) remember that the scientific method will prevent any changes to the current taxonomy and tree of life.
D) show the importance of genetic information as a characteristic of life.
E) propose a genetic relationship to living organisms and test how viruses lost life characteristics over time.