Answer:
option 2: B subunit.
Explanation:
RNA polymerase, an enzyme responsible for gene expression, synthesizes RNA from a DNA template. It recognizes promoter sequences on the DNA molecule, allowing RNA polymerase to bind and initiate transcription. The B subunit, also known as the sigma factor, facilitates this recognition, binding RNA polymerase to the promoter region of the DNA molecule. Other subunits, including A, B, and C, also play crucial roles.