If E Coli Is in an Environment That Is Rich in in Lactose

If E. coli is in an environment that is rich in lactose, a metabolite of lactose binds to

A) a repressor, releasing it from the operator site and activating transcription of the genes involved in lactose breakdown.
B) RNA polymerase, activating it to transcribe the genes involved in lactose breakdown.
C) an activator protein, which binds to RNA polymerase and stimulates transcription of the genes involved in lactose breakdown.
D) the operator site of the lac operon, stimulating transcription of the genes involved in lactose breakdown.