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
Not a Protease inhibitor is ? 
Select and explain. 
A. Nelfinavir, B. Saquinavir, C. Ritonavir, D. Abacavir
D: Abacavir
Answer: D: Abacavir 
Explanation: Ans. is 'd' i.e., Abacavir Antiretroviral drugs Nucleoside reverse transcriptase inhibitors (NIs) - Zidovudin, Didanosine, Zalcitabine, Stavudine, Lamivudine, Abacavir. Nucleotide reverse transcriptase inhibitor - Tenofovir (Katzung 10th/e) Nonucleoside reverse transcriptase inhibitors (NNIS) - Nevirapine, Eirenz, Delavirdine, Etravirine. Protease inhibitors - Ritonavir, Indinavir, Nelfinavir, Saquinavir, amprenavir, Lopinavir, Fosamprenavir, Atazanavir, Darunavir, Tipranavir. Fusion inhibitor - Enfuviide, Maraviroc. Integrase inhibitors - Roltegravir, Elvitegravir.