In the lac operon model, lactose molecules function as inducers, which bind with the repressor protein; inducers, which bind with the operator gene; repressors, which bind with the operator gene; or corepressors, which bind with repressors protein?

Inducer is a molecule that binds to repressor rendering it not able to bind to operator. In presence of lactose, allolactose; an isomer of lactose, binds to the repressor and causes an allosteric shift. The altered repressor can not bind to the operator, allowing RNA polymerase to transcribe the lac genes. Thus lactose serves as inducer. Correct answer is C.