The ionic equation for the reaction between aqueous copper ions and aqueous iodide ions is shown below. $2\text{Cu}^{2+}(aq) + 4\text{I}^-(aq) \rightarrow 2\text{CuI}(s) + \text{I}_2(aq)$ What is the change in oxidation state of copper?
- A+2 to $-1$
- B+2 to $0$
- C+2 to $+1$
- D+4 to $+2$