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: Anaesthesia
[{'content': 'When providing general anaesthesia during pregnancy, minimum alveolar concentration (MAC) is \nSelect and explain. \nA. Increased, B. Decreased, C. Unchanged, D. Variable', 'role': 'user'}, {'content': 'Answer: B \nExplanation: MAC progressively decreased during pregnancy.', 'role': 'assistant'}]