A 52-year-old man with chronic hepatitis C infection genotype 3 is started on a 12-week course of sofosbuvir/velpatasvir, a pan-genotypic direct-acting antiviral regimen. His baseline HCV RNA is 5.3 × 10^6 IU/mL. At week 4 of therapy and at the end of treatment, his HCV RNA is undetectable. Which of the following best defines a sustained virologic response (SVR) in this patient?