Phosphofructokinase (PFK) Is an Enzyme That Converts Fructose 6-Phosphate to Fructose

Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group.This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated.AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate.ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate.There are other regulators of this enzyme as well.What is the role of AMP in this example?

A) Competitive inhibitor
B) Noncompetitive inhibitor
C) Allosteric inhibitor
D) Allosteric activator