question: Q:A 60-year-old man comes to the physician’s office with jaundice. Liver ultrasound reveals a shrunken liver and biopsy reveals cirrhosis. Hepatitis serologies are below:
  
  Anti-HAV: negative
  HBsAg: negative
  HBsAb: positive
  HBeAg: negative
  Anti-HBe: negative
  Anti-HBc: negative
  Anti-HCV: positive
  
  The hepatitis C viral load is 1,000,000 copies/mL. The patient is started on an antiviral regimen including sofosbuvir. What is the mechanism of action of this drug?? 
  {'A': 'Inhibits synthesis of DNA-dependent DNA polymerase', 'B': 'Inhibits hepatitis C protease', 'C': 'Inhibits reverse transcriptase', 'D': 'Inhibits integrase', 'E': 'Inhibits RNA-dependent RNA polymerase'},