This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Viral Drugs, Subject name: Pharmacology
Which of the following antiviral drugs is used against HCV infection? 
Select and explain. 
A. Acyclovir, B. Sofosbuvir, C. Oseltamivir, D. Adefovir
B: Sofosbuvir
Answer: B: Sofosbuvir 
Explanation: Sofosbuvir is a direct acting anti-viral drug used against HCV infection. It is a nucleotide analog that inhibits HCV RNA polymerase (NS-5B). The active from of sofosbuvir competes with uridine triphosphate for incorporation into HCV RNA by NS5B polymerase. -Acyclovir: DOC for Herpes simplex virus 1 and 2 and also DOC for varicella zoster -Oseltamivir: DOC for bird flu and swine flu -Adefovir: Primarily used for HBV infection