Oxidation-Reduction Reactions Are Often Written with Double Arrows Indicating That

Oxidation-reduction reactions are often written with double arrows indicating that the reaction can go in either direction depending on the experimental conditions. For the following reaction identify the oxidizing agent on both sides of the chemical equation.
S₂O₈^2-(aq) + Zn(s) Zn²⁺(aq) + 2 SO₄^2-(aq)

A) S₂O₈^2- and SO₄^2-
B) Zn and SO₄^2-
C) Zn and Zn²⁺
D) S₂O₈^2- and Zn²⁺
E) none of these