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': 'All anesthetic agent decrease poal vein flow. Poal flow is maximally reduced by: \nSelect and explain. \nA. Ether, B. Halothane, C. Isoflurane, D. Enflurane', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. HalothaneAll volatile anesthetic agents reduce poal hepatic blood flow. This decrease is greatest with halothane and least with isofluraneQ.', 'role': 'assistant'}]