During the preparation of alkanes by Kolbe's electrolytic method using inert elecrodes,the pH of the electrolyte

Question

$\begin{array}{1 1}(a)\;\text{Decreases progressively as the reaction proceeds}\\(b)\;\text{Increases progressively as the reaction proceeds}\\(c)\;\text{Remains constant throughout the reaction}\\(d)\;\text{May decrease if the concentration of the electrolyte is not very high}\end{array}$