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
Apremilast acts by inhibiting : 
Select and explain. 
A. IL-17, B. CD25, C. PDE-4, D. IL-23
C: PDE-4
Answer: C: PDE-4 
Explanation: Apremilast is a PDE-4 inhibitor used in the treatment of Plaque psoriasis.