The Decomposition of Hydrogen Peroxide Is Given by the Following

The decomposition of hydrogen peroxide is given by the following reaction: 2 H₂O₂(aq) → 2 H₂O(l) + O₂(g)
In the presence of KI the reaction is thought to occur by the following mechanism:
Step 1: H₂O₂ + I^- → H₂O + IO^-
Step 2: IO^- + H₂O₂ → H₂O + O₂ + I^-
What is the role of I^- in this mechanism?

A) catalyst
B) frequency factor
C) product
D) transition state