This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'In muscle, phosphorylase b is inactivated by: \nSelect and explain. \nA. cAMP, B. Ca ions, C. Glucose, D. ATP', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. ATP', 'role': 'assistant'}]