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': 'Roflumilast is a \nSelect and explain. \nA. PDE-3 inhibitor, B. PDE-4 inhibitor, C. PDE-5 inhibitor, D. Leucotriene receptor antagonist', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Roflumilast is a PDE-4 inhibitor that inhibits degradation of cAMP and lead to bronchodilation.', 'role': 'assistant'}]