Read the passage given below and answer the following question.
The process of copying genetic information from one strand of the DNA into RNA is termed as transcription. Here also, the principle of complementarity governs the process of transcription, except the adenosine complements now forms base pair with uracil instead of thymine. A transcription unit in DNA is defined primarily by the three regions in the DNA. There is a convention in defining the two strands of the DNA in the structural gene of a transcription unit. Since the two strands have opposite polarity and the strand that has the polarity 3'→5' acts as a template, and is also referred to as template strand. The other strand which has the polarity (5'→3') and the sequence same as RNA (except thymine at the place of uracil), is displaced during transcription. Strangely, this strand (which does not code for anything) is referred to as coding strand. The promoter and terminator flank the structural gene in a transcription unit. It is a DNA sequence that provides binding site for RNA polymerase, and it is the presence of a promoter in a transcription unit that also defines the template and coding strands.

A Transcription unit in DNA is defined primarily by which regions in DNA?

All of the above

The correct answer is Option (4) → All of the above

The process of copying genetic information from one strand of the DNA into RNA is termed as transcription.However, unlike in the process of replication, which once set in, the total DNA of an organism gets duplicated, in transcription only a segment of DNA and only one of the strands is copied into RNA.

A transcription unit in DNA is defined primarily by the three regions in the DNA :
(i) A Promoter
(ii) The Structural gene
(iii) A Terminator

A) Promoter - This region signals the starting point of transcription and provides a binding site for RNA polymerase.

(C) Terminator - This region signals the end of transcription.

(D) The structural gene - This region contains the sequence that will be transcribed into RNA.