RNA can not acts as a/an
I) Messenger to dictate translation process
II) Structural molecule as a part of ribosomes
III) Adaptor molecule to carry amino acids
IV) Catalytic molecule for complete DNA replication

RNA though it acts as a genetic material in some viruses e.g., TMV.

It functions as a messenger molecule, e.g., mRNA

It functions as adaptor molecule, e.g., tRNA

It functions as a structural molecule, e.g., rRNA

In some cases as a catalytic molecule, e, e.g., Ribozyme. But can not acts catalytic molecule for complete DNA replication. Replication is by a set of different enzymes.