Answer:
The correct answer will be option-A
Explanation:
Sigma factor is a transcription initiation factor present in the prokaryotes and is composed of protein.
The sigma factor allows the binding of the specific RNA polymerase to the promoter of the gene. The binding of the sigma factor to the RNA polymerase form RNA polymerase holoenzyme which initiates the process of transcription.
The sigma factor dissociates once the initiation begins and the process of elongation has to begin leaving the core enzyme to carry out the elongation process.
Thus, option-A is the correct answer.
