Why have locks been created between the great lakes and the st. lawrence river?
a elevation between the areas is different
b to slow the shipping that goes through them
c to produce hydroelectricity
d to prevent flooding

"Elevation between the areas is different" is the option among the choices given in the question due to which locks have been created between the Great Lakes and the St. Lawrence River. The correct option among all the options that are given in the question is the first option or option "A". I hope it helps you.