Diagram A is the diagram where the protein is ready to be produced because the repressor protein is no longer attached to the DNA segment.
Option D.
Step-by-step explanation:
Lac operon is called the lactose operon which is present in bacteria which produces the lactose digesting enzymes. Lac operon is present in DNA from which three lactase enzymes are produced.
In lac operon, there are a few sites namely - cap site, promoter site, operator site, lac z, lac y, and lac a genes.
As lactose is absent in a cell, the RNA polymerase produces protein from the promoter region which gets attached with the operator region as repressor protein, this prevents the RNA polymerase to translate the lactase genes.
But if lactose is present in cell, then the lactose acts as inducer which joins with the repressor gene and the operator site remains free, and RNA polymerase is free to produce the genes from lac genes.