What must first occur for transcription to begin? mrna moves the code from the nucleus to the ribosome for protein production. a gene is expressed through protein production. rna polymerase attaches to the promoter. a repressor protein must attach to the operator.

RNA polymerase attaches to the promoter

Explanation:

Transcription is the process of synthesis of RNA using DNA as template. RNA polymerase enzyme binds to promoter region of the gene and starts making RNA strands that has complementary nucleotide sequence to DNA template strand. The process stops as the enzyme RNA polymerase encounter terminator sequence of gene.