In the given transcription unit,identify the regions $I$ and $II$ respectively.

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:

Give scientific reasons: Transcription and translation could be coupled in prokaryotic cell but not in eukaryotic cell.

In eukaryotes,the $mRNA$ that is initially transcribed is called:

Segments of $mRNA$ removed during splicing are called......

What function is performed by sigma factor and rho factor in the process of transcription?