This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
Besides zidovudine and lamivudine, which following drug is a reverse transcriptase inh v used in the treatment of HIV infection? 
Select and explain. 
A. Saquinavir, B. Indinavir, C. Abacavir, D. Ritonavir
C: Abacavir
Answer: C: Abacavir 
Explanation: Anti-Retroviral drugs (a) Nucleoside reverse transcriptase inhibitors (Nis) : Zidovudine (AZT), Didanosine, Zalcitabine*, Stavudine, Lamivudine, Abacavir (b) Nonnucleoside reverse transcriptase inhibitors (NNis) : Nevirapine, Eirenz, Delavirdine* (c) Protease inhibitors : Ritonavir, Indinavir, Nelfinavir, Saquinavir, Amprenavir*, Lopinavir Ref Harrison 20th edition pg 789