Answer:
attacks the outermost phosphorous group of the incoming nucleotide.
Explanation:
Transcription is the biological process where RNA is formed. As you may already know, RNA is an extremely important nucleic acid for genetic processes and the production of proteins. The transcription has three steps that are called start, elongation and end. In the elongation phase, the RNA strand is growing, at this time, RNA polymerase, which is the enzyme responsible for RNA elaboration, places the nucleotides, in the RNA strand, in the 5' - 3' direction. This enzyme causes the hydroxyl, which makes up the nucleotide at the 3' end of the forming RNA, to attack the phosphorus present in the incoming ribonucleotide.