This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Pharmacology), Subject name: Pharmacology
Which is a protease inhibitor? 
Select and explain. 
A. Azothymidine, B. Zidovudine, C. Squanavir, D. Acyclovir
C: Squanavir
Answer: C: Squanavir 
Explanation: (C) Squanavir