The Peroxodisulfate Ion Can Oxidize Iodide Ions to Iodine According $\rarr$

The peroxodisulfate ion can oxidize iodide ions to iodine according to the balanced equation S₂O₈^2- + 2I ^- $\rarr$ 2SO₄^2- + I₂.
The reaction is catalyzed by certain chemical species.Identify the catalyst in the following mechanism:
Step 1: Fe³⁺ + 2I ^- $\rarr$ Fe²⁺ + I₂
step 2: S₂O₈^2- + Fe²⁺ $\rarr$ 2SO₄^2- + Fe³⁺

A) Fe³⁺
B) I ^-
C) S₂O₈^2-
D) Fe²⁺
E) SO₄^2-