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: Pharmacology
[{'content': 'Mechanism of action of zileuton: September 2012, March 2013 \nSelect and explain. \nA. Cyclo-oxygenase inhibitor, B. 5-lipo-oxygenase inhibitor, C. 5-phospho-di-esterase inhibitor, D. Prevents mast cell degranulation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B i.e. 5-lip-oxygenase inhibitor', 'role': 'assistant'}]