The lac operon is a system that can be both inducible and repressible. How does this compare to the trp operon?

• A. The trp operon is also both inducible and repressible
• B. The trp operon is an inducible system only
• C. The trp operon is a constitutive system
• D. The trp operon is a repressible system

Answer: (D)