The potato spindle tuber disease is caused by which of the following?

Which one of the following statements about viruses is correct?

In the given figure,what do 'a' and 'c' represent respectively?

Assertion $A$: Viruses are considered as a link between living and non-living organisms.
Reason $R$: Viruses are non-living,but they are obligate parasites in living cells.
Which option is correct for Assertion $A$ and Reason $R$?

Viruses are known as:

The best supporting fact that "Viruses are living" is that viruses