Which of the following regions are present in the transcription unit…

The correct answer is Option (4) → (A), (B) and (D) only

A transcription unit is the stretch of DNA that is copied into RNA. It has three regions: a promoter, a structural gene and a terminator.

(A) A Terminator — Correct. The terminator lies at the end (3′ end of the coding strand) of the structural gene. It marks where transcription stops.

(B) A Promoter — Correct. The promoter lies before (upstream of) the structural gene. RNA polymerase binds here, so it marks where transcription starts.

(C) The initiation factor — Incorrect. An initiation factor is a protein that joins RNA polymerase to start transcription. It is not a region of the DNA.

(D) The Structural gene — Correct. The structural gene lies between the promoter and the terminator. This is the part that is copied into RNA.

Note: A similar question was also asked in CUET (UG) 2025 on 23-05-2025 (Slot 2), and in CUET (UG) 2023 on 15-06-2023 (Slot 1).

NCERT Extract:
Transcription Unit – “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 There is a convention in defining the two strands of the DNA in the structural gene of a transcription unit.”