What Is the Function of the Group of Amino Acids

What is the function of the group of amino acids on the RNA polymerase called the rudder?

A) It provides the energy required for formation of phosphodiester bonds in the elongation RNA molecule.
B) It helps unwind and open the DNA molecule.
C) It moves template and non-template strands of DNA through channels inside the enzyme.
D) It helps sigma bind to the RNA polymerase molecule.