Which statement best describes a repressilator, a synthetic biology oscillator?

Which statement best describes a repressilator, a synthetic biology oscillator?

• A. A circuit that permanently expresses a single gene.
• B. A toggle switch based on mutual repression.
• C. An oscillator (for example, repressilator) that uses delayed negative feedback for periodic expression.
• D. A circuit that inactivates all transcription.

Answer: (C)