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: Physiology
[{'content': 'Highest conduction rate in m/s is observed in: \nSelect and explain. \nA. SA node, B. AV node, C. Bundle of His, D. Purkinje system', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. Purkinje system', 'role': 'assistant'}]