Apply half-equations and oxidation numbers to balance redox equations (acid conditions only) and to discriminate between the species oxidised and reduced, and the oxidising agent and reducing agent.

In the redox reaction between dichromate ions and iodide ions in acidic solution, the unbalanced equation is: $$\text{Cr}_2\text{O}_7^{2-}(aq) + \text{I}^-(aq) + \text{H}^+(aq) \rightarrow \text{Cr}^{3+}(aq) + \text{I}_2(aq) + \text{H}_2\text{O}(l)$$ Which of the following correctly identifies the species oxidised and the oxidising agent?