ANS:D - all of the above

Phospho kinase 1 enzyme has about 4 active sites i.e active site for ATP, Citrate, AMP & Fructose 2-6 Bisphosphate site, Increase in Fructose 2-6 Bisphosphate (a very powerful stimulant of Phospho Kinase 1).

ATP & Citrate, signals Phospho Kinase 1 to Phosphorylate more Fructose 6 phosphate into Fructose 1-6 bisphosphate. In my opinion this is the Enzymatic Allosteric Regulation.