The Purpose of the Gene Products of the Lac Operon

The purpose of the gene products of the lac operon is to ___________.The purpose of the gene products of the trp operon is to ___________.

A) Produce lactose when glucose is low; produce tryptophan when tryptophan is low.
B) Produce lactose when lactose is low; produce tryptophan when glucose is low.
C) Produce lactose when glucose is low; metabolize tryptophan for energy.
D) Metabolize lactose when glucose is low; metabolize tryptophan for energy.
E) Metabolize lactose when glucose is low; produce tryptophan when tryptophan is low.