This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Bio-Chemistry), Subject name: Biochemistry
[{'content': 'In muscle, phosphorylase b is kept in inactivated state by \nSelect and explain. \nA. cAMP, B. ATP, C. Calcium, D. Glucose', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) cAMP', 'role': 'assistant'}]