In which of the following reactions, $H_2O_2$ acts as a reducing reagents ?

Question

( A ) $PbO_2 (s) + H_2O_2 (aq) \to PbO (s) + H_2O (l) + O_2 (g)$
( B ) $Na_2SO_3 (aq) + H_2O_2 (aq) \to Na_2SO_4 (aq) + H_2O (l)$
( C ) $KNO_2(aq) + H_2O_2 (aq) \to KNO_3 (aq) + H_2O (l)$
( D ) $2KI (aq) + H_2O_2 (aq) \to 2KOH (aq) + I_2 (s)$