The correct answer is:
D). It cannot attach to the promoter.
It cannot attach to the promoter. Only the proteins that the bacteria Escherichia coli (E. coli) needs are integrated at any given time. A transcription factor can operate as a transcription activator as strong as a transcription repressor. The same transcription factor can work as a repressor for a group of genes and activator for another group. Such function has temporary and/or spatial specificity. A number of oncogenes are transcriptional activators during early development but repressor through adulthood, their strange expression drives to cell proliferation and tumor development/oncogenesis.
The answer is It cannot attach to the promoter. The operator is usually close to the promoter region. When the suppressor protein attached to the operator , it physically acts as a barrier that prevents the RNA polymerase from binding on the operator. This is a transcriptional negative regulation of a gene in most cells.
It cannot attach to the promoter.
If a repressor protein attaches to the operator, RNA polymerase cannot proceed to transcribe key enzymes needed by the organism. This can be seen in the trp operon in E .coli bacteria.