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
[{'content': 'Phosphorylase b is maintained in an inactivated state by \nSelect and explain. \nA. ATP, B. cAMP, C. Calcium, D. Insulin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Question is repeasted', 'role': 'assistant'}]