Which of the following statements about regulation of the lac operon is true? When glucose is present, gene expression is activated by lactose. The amount of glucose in the growth medium does not affect the level of gene expression activated by lactose. The Lac repressor can dissociate from the operator in the presence of glucose. Gene expression is high when the Lac repressor is not bound to the operator and glucose is unavailable. Gene expression is high when the Lac repressor is not bound to the operator and glucose and lactose are available.