Which reaction is not a redox reaction?
- A$\text{Mg} + 2\text{HNO}_3 \rightarrow \text{Mg(NO}_3)_2 + \text{H}_2$
- B$2\text{Mg(NO}_3)_2 \rightarrow 2\text{MgO} + 4\text{NO}_2 + \text{O}_2$
- C$\text{SO}_2 + \text{NO}_2 \rightarrow \text{SO}_3 + \text{NO}$
- D$\text{SO}_3 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_4$