The correct answer is A. Waltz’s three images of international relations meant denote for the three possible sources of war in international relations because Waltz refers to the three levels of analysis as “images”. In that he explained sources of international behavior, (manifested as foreign policy) in human nature (first image), organizations and structures of the state and struggles among domestic actors (second image), in the structure of the international system, relationships among states and groups of states, alliances etc. (third image). He essentially underrated the explanatory power of the first and second images and concentrated on the third as the main level of analysis to understand causes of war, and international relations as such. As it focused on the systemic sources Waltz’s argument is structural.