The correct balanced equation for the single replacement reaction of magnesium with aluminum oxide (Al₂O₃) is:
C: \( 3 \text{Mg} + \text{Al}_2\text{O}_3 \rightarrow 3 \text{MgO} + 2 \text{Al} \)
This represents the reaction where three magnesium atoms displace aluminum from aluminum oxide, producing magnesium oxide and aluminum as products.