Which of the following is non-genetic and is utilized for protein synthesis?

Which of the following discoveries led to the term '$RNA$ world' being coined in $1980$?

Given below are two statements:
Statement $I$: $RNA$ mutates at a faster rate.
Statement $II$: Viruses having $RNA$ genome and shorter life span mutate and evolve faster.
In the light of the above statements,choose the correct answer from the options given below:

The smallest $RNA$ is........

In some viruses,$RNA$ is present instead of $DNA$ indicating that

How many main types of $RNA$ are there?