Transcriptional Activation of the Lac Operon Requires Both High Lactose

Transcriptional activation of the lac operon requires both high lactose and low glucose conditions because:

A) RNA polymerase requires CAP in order to bind to the lac operon promoter, even in the absence of the repressor.
B) glucose normally activates the lac operon repressor.
C) RNA polymerase is inactive in the presence of high glucose concentrations.
D) high glucose concentrations stimulate CAP activity.
E) glucose and lactose compete for binding to, and inactivation of, the lac operon repressor.