Final answer:
The provided information does not specify which countries were exclusively studied for the impact of war. References are made to Europe, Asia, and the United States, and the global nature of World Wars I and II, suggesting a broad international scope.
Step-by-step explanation:
The student's question regarding which countries were studied for the impact of war cannot be definitively answered based on the provided information. The text discusses the impact of World War I and II on various countries and continents, mentioning Europe, Asia, and the United States, but does not specify an exclusive study on the impact of war for a certain group of countries. For example, the text mentions that African, Asian, and Latin American economies felt the economic effects of World War I. It also notes the experiences of European nations such as Britain and France, as well as East Asian countries like China and Japan post-World War I.
Moreover, the origins of World War II are discussed from different historical perspectives, indicating how various countries might view the start of the war. The global nature of the conflicts is highlighted by referencing military engagements in various parts of the world, including Europe, the Middle East, Africa, and Asia. Consequently, the countries or continents that experienced the most dramatic changes cannot be conclusively determined based on the excerpts. These points allude to the diverse international impacts and the global aspect of the wars, suggesting that many nations were studied concerning the impact of war.