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': 'All of the following enzymes are regulated by calcium or calmodulin, except: \nSelect and explain. \nA. Adenylate cyclase, B. Glycogen synthase, C. Guanylyl cyclase, D. Hexokinase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Adenyl cyclase, guanylate cyclase and glycogen synthase enzymes (but not hexokinase) are activated by calcium and calmodulin.', 'role': 'assistant'}]