GKFix MCQ Question

In H₃PO₂ + 4AgNO₃ + 2H₂O → H₃PO₄ + 4Ag + 4HNO₃, what is reduced?

• A. H₃PO₂
• B. Ag⁺
• C. HNO₃
• D. H₃PO₄