A transcription factor or sigma factor binds to DNA at the promoter.

a. initiation

b. elongation

c. termination

The correct answer will be option-A.

Explanation:

The transcription of bacteria is divided into three stages: initiation, elongation and termination.

The transcription process initiates when a specificity factor of RNA polymerase enzyme called sigma factor binds the promoter region of the DNA. The sigma factor ensures the binding of the RNA polymerase enzyme to the promoter region at the start site. After the transcription process starts, the sigma factor falls of the strand and enzyme transcript the DNA to RNA.

Thus, option-A is the correct answer.