Which of the following is one role of RNA polymerase during transcription?

to switch uracil with thymine on the exposed gene

to build a molecule of mRNA

to break down an already existing protein

to produce a start sequence

RNA polymerase performs the function of producing messenger RNA, also known as mRNA, while using DNA strand as the template. It binds to DNA strand and synthesizes RNA strand, which is complementary to the DNA strand in terms of bases. This mRNA is then translated into protein in cytoplasm at ribosomes. One mRNA transcript can be used to synthesize multiple copies of protein. Also, eukaryotes contain three types of RNA polymerase, each with its different set of functions.