Final answer:
The sigma (σ) subunit of RNA polymerase establishes template binding to a promoter in prokaryotes during transcription initiation. Option c
Step-by-step explanation:
In prokaryotes, the subunit of RNA polymerase that establishes template binding to a promoter is the sigma (σ) subunit.
The sigma subunit is involved in transcription initiation and recognizes consensus sequences found in the promoter region upstream of the transcription start site.Once transcription is initiated, the sigma subunit dissociates from the polymerase. The sigma subunit's primary role in this process involves recognizing consensus sequences in the promoter region upstream of the transcription start site. This action ensures that the polymerase initiates transcription at specific, proper sites instead of random locations, which would result in non-functional mRNA. After transcription has been initiated, the sigma subunit dissociates from the polymerase.