Classical liberalism emerged as a response to the Industrial Revolution and urbanization in the 19th century in Europe and the United States, a time when dehumanizing aspects of the social order were of concern to many. It was also a turn away from the traditional central focus of International Relations, the development of sovereign states. As also understood from the information givent, the correct answer is D. The information taking place in the fourth option is related to realism. To Morgenthau, realism is a power politics theory. That is, it focuses on how power contributes to a variety of political outcomes and to a        state’s  security, and by its assumptions, concludes there can be little security for any weak state (one with little power).