Inducible genes are usually actively transcribed when:

A) an inducer inactivates the repressor.
B) repressor molecules bind to the promoter.
C) lactose is absent from the cell.
D) expression of repressor genes is turned off.
E) energy is not needed by the cell.

Inducible genes are typically turned on (actively transcribed) when an inducer molecule binds to a repressor protein, thereby inactivating the repressor and allowing transcription to proceed. This mechanism is exemplified in the lac operon of E. coli, where the presence of lactose (the inducer) inactivates the repressor, leading to the transcription of genes involved in lactose metabolism.