Gene regulation governing the lactose operon of $E. coli$ that involves the $lac I$ gene product is:

• A
  negative and repressible because the repressor protein prevents transcription.
• B
  feedback inhibition because excess of $\beta$-galactosidase can switch off transcription.
• C
  positive and inducible because it can be induced by lactose.
• D
  negative and inducible because the repressor protein prevents transcription.