A correct electrochemical series can be obtained from K, Na, Ca, Al, Mg, Zn, Fe,...

The electrochemical series is a list of elements in order of their standard electrode potentials. Elements at the top of the series are more reactive and tend to lose electrons (oxidation) more easily, while elements at the bottom are less reactive and tend to gain electrons (reduction) more easily.

For this question, we need to find the correct order of the elements in the electrochemical series. The correct order is K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au. Comparing this order with the given order, you can see that Al and Mg need to be interchanged to obtain the correct electrochemical series.

Therefore, the correct answer is Option A: Al and Mg.

Knowing the correct order of the electrochemical series is important because it allows you to predict the outcomes of redox reactions and determine which elements will act as reducing or oxidizing agents in those reactions.