How do the lac operon and trp operon illustrate opposing gene regulation mechanisms?

• A. The lac operon is activated by lactose, whereas the trp operon is also activated by tryptophan.
• B. The lac operon is activated by an inducer, whereas the trp operon is repressed by a corepressor.
• C. The lac operon is repressed by glucose, whereas the trp operon is induced by low tryptophan levels.
• D. The lac operon is continuously expressed without lactose, whereas the trp operon is always repressed by tryptophan.

Answer: (B)