Identify $X$ in the given figure.

During transcription,the holoenzyme $RNA$ polymerase binds to the $DNA$ strand. It forms a structure resembling a saddle at a specific site on the $DNA$. This sequence is called .....

What is the location of the terminator in a transcription unit?

The process of removal of introns in a defined order in a transcription unit is called . . . . . . .

$A$: Sigma factor of $RNA$ polymerase recognizes the start signal region in prokaryotes.
$R$: Promoter region lies at $5'$ end of the coding strand, not the template strand.

Given below are the two statements.
Statement $I$: Only one strand in the transcription unit functions as a template and is called the antisense strand.
Statement $II$: The non-template strand of the transcription unit is called the sense strand.
In the light of the above statements,choose the correct answer from the options given below.