This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inhalational Anesthetic Agents, Subject name: Anaesthesia
[{'content': 'What is the effect of 1-2 MAC dose of volatile anaesthetic agents on EEG waveforms- \nSelect and explain. \nA. b-a-th-S, B. S-th-a-b, C. b -th-S- a, D. a - th-S- b', 'role': 'user'}, {'content': 'Answer: A \nExplanation: EEGs recorded on the scalp can be processed to quantify the amount of activity in each of four frequency bands: Delta (o to 3hz), Theta (4 to 7 Hz) alpha (8 to 13 Hz), Beta (> 13 Hz) Between 1-2 MAC shift is towards decreased frequency. b-a-th-S', 'role': 'assistant'}]