You have created a fusion between trp operon and lac operon which encodes the enzymes for tryptophan biosynthesis, under the regulatory control of the lac operator. Under which of the following conditions will tryptophan synthase be induced in the strain that carries the chimeric operator fused operons ?

Options

A. Only when both lactose and glucose are absent
B. Only when both lactose and glucose are present
C. Only when lactose is absent and glucose is present
D. Only when lactose is present and glucose is absent

Answer

d