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
Mechanism of action of zileuton: September 2012, March 2013 
Select and explain. 
A. Cyclo-oxygenase inhibitor, B. 5-lipo-oxygenase inhibitor, C. 5-phospho-di-esterase inhibitor, D. Prevents mast cell degranulation
B: 5-lipo-oxygenase inhibitor
Answer: B: 5-lipo-oxygenase inhibitor 
Explanation: Ans. B i.e. 5-lip-oxygenase inhibitor