Phosphofructokinase Is Regulated by a Number of Factors, Including High

Phosphofructokinase is regulated by a number of factors, including high levels of ATP.Why is this enzyme regulated by ATP levels?

A) If ATP levels are high, this provides a mechanism to directly inhibit the Krebs cycle, thus preventing further generation of NADH, FADH₂ and ATP molecules that are not needed.
B) If ATP levels are high, it is important to directly inhibit the reaction that commits the substrate to glycolysis to allow the substrate to be available for other reactions, since the cell has ample energy.
C) If ATP levels are high, it is important to inhibit ATP synthase, and phosphofructokinase directly inhibits ATP synthase.
D) If ATP levels are high, this provides a mechanism to directly inhibit the electron transport chain, thus preventing the formation of a proton gradient in the intermembrane space of mitochondria.