What Is the Reducing Agent in the Reaction 8 Na₂CO₃(s) $\to$

What is the reducing agent in the reaction 8 Na₂CO₃(s) + 4 FeCr₂O₄(s) + 7 O₂(g) $\to$ 8 Na₂CrO₄(s) + 2 Fe₂O₃(s) + 8 CO₂(g) ?

A) Na₂CO₃
B) FeCr₂O₄
C) O₂
D) Na₂CrO₄
E) 2Fe₂O₃