This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
Allosteric stimulator of glycogen phosphorylase 
Select and explain. 
A. ATP, B. AMP, C. Insulin, D. Glucose-6-phosphate
B: AMP
Answer: B: AMP 
Explanation: AMP formed by degradation of ATP during muscle contraction is an allosteric activator of phosphorylase b. The calcium binds calmodulin and the complex activates phosphorylase kinase.Ref: DM Vasudevan, 7th edition, page no: 129