Who isolated protein and nucleic acid from nuclein?

The unequivocal proof of $DNA$ as the genetic material came from the studies on a

Recall the experiments done by Frederick Griffith,Avery,MacLeod,and McCarty,where $DNA$ was speculated to be the genetic material. If $RNA$,instead of $DNA$,was the genetic material,would the heat-killed strain of $Pneumococcus$ have transformed the $R$-strain into a virulent strain? Explain.

Nucleic acid was first discovered from . . . . . . .

The unequivocal proof that $DNA$ is the genetic material was given by whom?

What was the transforming principle identified by Avery,MacLeod,and McCarty in Pneumococcus?