The author implies that, after certain territories and countries had been joined into an interdependent market system in the nineteenth century, agrarian depressions within that system A. spread to several nations, excluding those in which the internal frontier remained open B. manifested themselves in several nations, including those in which new land remained available for farming C. slowed down the pace of new technological developments in international communications and transportation D. affected the local and national prices of the nonagricultural products of several nations E. encouraged several nations to sell more of their agricultural products on foreign markets