When the pH of the system is increased by 2.0 units, maximum decrease in half cell potential for the reaction will be observed in

A

$$\text{V}^{2+}(aq) \rightarrow \text{V}^{3+}(aq) + e^-$$

B

$$\text{VO}_3^-(aq) + 2\text{H}^+ \rightarrow \text{VO}_2^+ + \text{H}_2\text{O}$$

C

$$\text{VO}^{2+} + 2\text{H}^+ + e^- \rightarrow \text{V}^{3+} + \text{H}_2\text{O}$$

D

$$\text{VO}^{2+} + \text{H}_2\text{O} \rightarrow \text{VO}_2^+ + 2\text{H}^+ + e^-$$