How does lactose presence influence Lac operon expression in E. coli?

• A. Lactose directly binds RNA polymerase to start transcription.
• B. Lactose binds to the operator to block transcription.
• C. Lactose (via allolactose) binds to the repressor, inactivating it and allowing transcription.
• D. Lactose prevents repressor binding by altering DNA conformation.

Answer: (C)