Part A is being done in treatment-naïve (TN), genotype 1 (GT1), interferon eligible, non-cirrhotic (N-C) participants with chronic hepatitis C (CHC). Participants will be assigned randomly to 1 of 2 treatment arms in which they will receive grazoprevir 100 mg once daily (QD) + elbasvir 20 mg or 50 mg QD and twice daily (BID) RBV, or to a treatment arm in which they will receive grazoprevir 100 mg QD + elbasvir 50 mg QD without RBV. Treatment will last 12 weeks.