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': 'The volatility of an anesthetic agent is directly propoional to lowering the flow in the poal vein. Poal flow is maximally reduced by: \nSelect and explain. \nA. Ether, B. Halothane, C. Isoflurane, D. Enflurane', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Halothane reduces splanchnic and hepatic blood flow as a consequence of reduced perfusion pressure. This reduced blood flow has not been shown to produce detrimental effects on hepatic or GI function. The metabolism and clearance of some drugs (eg, fentanyl, phenytoin, verapamil) appear to be impaired by halothane. Ref: Morgan, Jr. G.E., Mikhail M.S., Murray M.J. (2006). Chapter 7. Inhalation Anesthetics. In G.E. Morgan, Jr., M.S. Mikhail, M.J. Murray (Eds), Clinical Anesthesiology, 4e.', 'role': 'assistant'}]