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': 'EEG rhythm having lowest frequency is? \nSelect and explain. \nA. Alpha, B. Beta, C. Delta, D. Theta', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Delta', 'role': 'assistant'}]