Why is the tryptophan operon described as repressible and how is it regulated?

Why is the tryptophan operon described as repressible and how is it regulated?

• A. The operon is not regulated by tryptophan.
• B. The repressor is inactivated in high tryptophan conditions, allowing transcription.
• C. The operon is active only when tryptophan is absent.
• D. High tryptophan enables binding of the repressor with tryptophan as a co-repressor, stopping transcription.

Answer: (B)