A. mRNA is made by RNA polymerase, using DNA as a template
Explanation:
An mRNA molecule is synthesized by RNA polymerase which uses DNA template to do so. In eukaryotes, mRNA is specifically synthesized by RNA ploymerase II with the help of sigma factor and various transcription factors while tRNA and rRNA are synthesized by RNA polymerase III & I respectively. But in contrast to eukaryotes, in prokaryotes a single RNA ploymerase synthesizes mRNA as well as tRNA and rRNA with the help of sigma factor.
