Which of the following statements are correct with reference to a transcription unit?
$A$. $A$ transcription unit in $DNA$ is defined primarily by three regions: promoter, structural gene and terminator.
$B$. The promoter is said to be located towards the $5'$-end of the structural gene.
$C$. The promoter is a $DNA$ sequence that provides binding site for $RNA$ polymerase.
$D$. The promoter defines the template and coding strands.
$E$. The terminator is located towards the $3'$-end of the coding strand and it defines the end of the process of transcription.
Choose the correct answer from the options given below:

• A
  $(1)$ $B, C, D$ and $E$ only
• B
  $(2)$ $A, B, C, D$ and $E$
• C
  $(3)$ $A, B, C$ and $D$ only
• D
  $(4)$ $A, C, D$ and $E$ only