How is $m-RNA$ synthesized?

• A
  $m-RNA$ is synthesized by the genes of a $DNA$ segment.
• B
  $m-RNA$ is synthesized by $t-RNA$ with the help of $DNA$.
• C
  $m-RNA$ is synthesized by $t-RNA$.
• D
  $m-RNA$ is synthesized by $t-RNA$ and $r-RNA$.