Which of the following statements correctly compares metalloenzymes and activator ions?

• A. Both metalloenzymes and activator ions have tightly bound transition metals.
• B. Both metalloenzymes and activator ions have loosely bound alkali metals.
• C. Metalloenzymes have loosely bound alkali metals, while activator ions are tightly bound transition metals.
• D. Metalloenzymes have tightly bound transition metals, while activator ions are loosely bound alkali metals.