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
Roflumilast is a 
Select and explain. 
A. PDE-3 inhibitor, B. PDE-4 inhibitor, C. PDE-5 inhibitor, D. Leucotriene receptor antagonist
B: PDE-4 inhibitor
Answer: B: PDE-4 inhibitor 
Explanation: Roflumilast is a PDE-4 inhibitor that inhibits degradation of cAMP and lead to bronchodilation.