Final answer:
In the lac operon, the repressor binds to the operator site, which is located near the lac promoter. The operator is the correct DNA sequence repressor binding site in the context of the lac operon.
Step-by-step explanation:
In the lac operon, the repressor binds to a DNA sequence called the operator site. This site is indeed located near the lac promoter. The correct answer to the question is a) Operator.
The lac operon is a well-studied example of gene regulation in bacteria. The repressor protein, which is continually produced by the I gene of the lac operon, can bind to the operator site under certain conditions. When lactose is not present, the repressor is bound to the operator, preventing RNA polymerase from transcribing the downstream genes that are needed for lactose metabolism. However, when lactose is present and converted to allolactose, it binds to the repressor making it unable to bind to the operator. This allows RNA polymerase to bind to the lac promoter and initiate transcription of the genes necessary for lactose utilization.