This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'All are involved in cardiac conduction pathway except: \nSelect and explain. \nA. SA node, B. Purkinje fibers, C. Bundle of His, D. Sarcomere', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans: D (Sarcomere) Ref: Ganong's Review of Medical Physiology. 21st ed.Explanation:Cardiac Conduction PathwaySA nodeAV nodeBundle of HisLeft and right bundle branchPurkinje fibres", 'role': 'assistant'}]