In which reaction is the largest change in sulfur’s oxidation number observed?
- A$\text{S}(s) + \text{O}_2(g) \rightarrow \text{SO}_2(g)$
- B$\text{SO}_2(g) + \frac{1}{2}\text{O}_2(g) \rightleftharpoons \text{SO}_3(g)$
- C$\text{SO}_3(g) + \text{H}_2\text{SO}_4(l) \rightarrow \text{H}_2\text{S}_2\text{O}_7(l)$
- D$\text{H}_2\text{S}_2\text{O}_7(l) + \text{H}_2\text{O}(l) \rightarrow 2\text{H}_2\text{SO}_4(l)$