So let's focus on D. So essentially, in order to inactivate the phosphoralase kinase, what happens is the PKA must phosphorylate the alpha subunits of Asphylase kinase. So the same PKA that is used to activate phosphorylase kinase is also actually used to inactivate phosphorase kinase. Remember when PKA phosphorylates the beta subunits, that activates this, but when PKA phosphorlates the alpha subunits, that causes the phosphorylase kinase to become a good substrate for another protein known as PP one, which stands for protein phosphatase one. And what happens is once PTA phosphorlates the alpha subunits, the phosphorlase kinase acts as a substrate to protein phosphatase one, and protein phosphatase one basically defosphorylates the beta subunits of phosphorase kinase and that inactivates this molecule. So PKA phosphorlates the alpha units of phosphorlase kinase, which in turn makes it a good substrate molecule for protein phosphatase one. PP one and PP one removes the phosphoryl groups from the beta subunits and this deactivates the other kinase.