The ionic half-equation for oxygen being produced in the electrolysis of aluminium oxide is given below. $x\text{O}^{2-} \rightarrow \text{O}_2 + y\text{e}^-$ What values do $x$ and $y$ have?
- A$x = 1,\; y = 2$
- B$x = 1,\; y = 4$
- C$x = 2,\; y = 2$
- D$x = 2,\; y = 4$