A universal indicator solution is introduced into a neutral concentrated aqueous sodium chloride solution. This solution contains $\text{H}^+$ (hydrogen), $\text{Na}^+$ (sodium), $\text{Cl}^-$ (chloride) and $\text{OH}^-$ (hydroxide) ions, and it is electrolysed. Hydrogen gas is formed at the cathode, while chlorine gas is produced at the anode. What colour change does the indicator in the solution undergo during electrolysis?
- AThe colour changes from blue to green.
- BThe colour changes from blue to red.
- CThe colour changes from green to blue.
- DThe colour changes from green to red.