Which of the following best describes the genes and their functions in the lac operon?

• A. The lac operon contains one gene: lacI, which encodes the repressor protein.
• B. The lac operon contains four genes responsible for glucose metabolism.
• C. The lac operon contains two genes: lacY and lacA, both involved in tryptophan synthesis.
• D. The lac operon contains three genes: lacZ, lacY, and lacA. LacZ encodes β-galactosidase, lacY encodes permease, and lacA encodes transacetylase.

Answer: (D)