In which of the following reactions does hydrogen peroxide act as a reducing agent?

a) 2H₂O₂ →2H₂O+O₂
b) 2H₂O₂ →2H₂O+2O
c) H₂O₂+2MnO⁻₄ →2MnO₂+2H₂O+O₂
d) H₂O₂ →H₂O+1/2O₂