Who discovered the virus for the first time?

Viruses are ...........

Assertion $(A)$: Viruses are considered as a link between living and non-living things.
Reason $(R)$: Viruses are inactive and behave like non-living matter in a free state,whereas they show active and living behavior inside a host cell.

Which of the following is an example of an animal virus?

Which one is the smallest among the following?

Which option is correct for the subunits of a viral capsid?