Final answer:
The Variolavirus is the largest, followed by the Orthomyxovirus, and the Poliovirus is the smallest among the three mentioned viruses.
Step-by-step explanation:
We can rank the following viruses from largest to smallest: Variolavirus (cause of smallpox), Orthomyxovirus (which includes influenza viruses), and Poliovirus. The Variolavirus is known to be larger than many viruses, with a size range reflecting its complex structure. The Orthomyxovirus, which includes Influenza types A and B, has a size typically smaller than the Variolavirus. Lastly, the Poliovirus is much smaller, with an icosahedral shape and is among the viruses that are on the smaller side of the spectrum.