Sodium Thiosulfate, Na₂S₂O₃, Is Used as a "Fixer" in Black $\rightarrow$

Sodium thiosulfate, Na₂S₂O₃, is used as a "fixer" in black and white photography. Identify the reducing agent in the reaction of thiosulfate with iodine. 2S₂O₃^2¯(aq) + I₂(aq) $\rightarrow$ S₄O₆^2¯(aq) + 2I^¯(aq)

A) I₂(aq)
B) I^¯(aq)
C) S₂O₃^2¯(aq)
D) S₄O₆^2¯(aq)
E) S₂O₃^2¯(aq) and I^¯(aq)