Physics – Electric Potential | Nursing School Essays

Physics – Electric Potential | Nursing School Essays

picture to go with ranking question 
Using the diagram provided in the link, rank each of the given paths on the basis of the change in electric potential. Rank the largest-magnitude positive change (increase in electric potential) as largest and the largest-magnitude negative change (decrease in electric potential) as smallest.
So far I have c to d holding the highest potential since they are equivalent. Then b to a next since it is the closest to the positive charge. However I have no idea where to do from here and I have tried multiple rankings and none of them seem to work out.
Do any equations help in determining the ranking? How can I better understand how to derive the answer to this question? 
Any help would be great.