According to Karl Marx, social change results from the efforts of <span>the powerless to gain power. The correct option among all the options that are given in the question is the first option or option "a". I hope that this is the answer that you were looking for and it has actually come to your help.</span>
They used the Apalachian mountains. Hope this helped.
Its a multilateral system of trading in which a country pays for its imports from one country by its exports to another. Hope this answers your question :)
The correct answer is Thorndike, Skinner and Bandura.