When electric current is passed through a conducting solution, there is a change of colour of the solution. This indicates

Question

$\begin{array}{1 1} \text{(a) the chemical effect of current.} \\ \text{ (b) the heating effect of current.} \\ \text{ (c) the magnetic effect of current.} \\ \text{ (d) the lightning effect of current.} \end{array}$