Which of the following is not a step in transcription?

-RNA polymerase unwinds the double helix of the transfer RNA


-RNA polymerase attaches to a gene's promotor region on a strand of DNA


-RNA polymerase adds complementary RNA nucleotides to the growing strand of RNA


-RNA polymerase unwinds and separates the DNA strands|||D is not ( a, b and c, are alright)|||Why should RNA polymerase unwind transfer RNA and where is double helix in transfer RNA? This is an inappropriate statement.