The correct answer is C. In his seminal book Politics Among Nations: The Strugglefor Power and Peace, originally published in 1948, Hans J. Morgenthau, one of the great thinkers of the classical realist school of international relations, has placed “interest defined as power” as the “link between reason trying to understand international politics and the facts to be understood” as “statesman think and act in terms of interest defined as power”, (Morgenthau, 1993, p.5)