You will be given a definition of a task first, then some input of the task.
In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.

They give their permission through their elected representatives ( Rule by the People ) , who is the source of all political power .
Output:
Popular sovereignty is the principle that the authority of a state and its government are created and sustained by the consent of its people , through their elected representatives ( Rule by the People ) , who are the source of all political power .