What is the lac operon and how is it activated?

• A. The lac operon is a repressible operon that is turned on by the presence of tryptophan.
• B. The lac operon is a constitutive operon that is always active.
• C. The lac operon is an inducible operon that is turned on by the presence of allolactose.
• D. The lac operon is activated by glucose binding to the operator.

Answer: (C)