Answer the following question given this paragraph: 

When lactose is available, a lactose metabolite called allolactose binds to the allosteric site on the repressor. This interaction causes a conformational change in the repressor shape and the repressor falls off the operator, allowing RNA polymerase to bind to the promoter and initiate transcription. Allolactose is called an inducer because it turns on, or induces the expression of the lac genes.


Q: Which inducer turns on the expression of the lac genes?


A:
allolactose