Why is fructose 2,6-bisphosphate effective at low concentrations in activating phosphofructokinase 1?

• A. It is a cofactor required for phosphofructokinase 1 activity.
• B. It binds to the active site of phosphofructokinase 1, increasing its affinity for substrates.
• C. It acts as a competitive inhibitor of phosphofructokinase 1.
• D. It is a product of the reaction catalyzed by phosphofructokinase 1.

Answer: (B)