Final answer:
The principle of 'Major battles and outcomes' is the most effective for organizing the history of World War II, as it captures the war's scale, progression, and defining moments which shaped the post-war world.
Step-by-step explanation:
The most effective organizing principle for writing the history of World War II would likely be b. Major battles and outcomes. This approach allows for a comprehensive overview of the war, incorporating diverse events, strategies, and their impacts on the overall conflict. Highlighting major battles illustrates the scale, the tactical and strategic evolution of the war, and the shifts in momentum that determined its outcome. This principle also underscores pivotal moments such as D-Day, the Battle of Stalingrad, and the use of atomic bombs on Hiroshima and Nagasaki, which are widely recognized and debated as turning points with significant effects not only on the war’s direction but also on shaping the post-war world.
Additionally, by focusing on major battles and outcomes, one can also weave in related topics such as the roles of World leaders of the time period, the atrocities of major concentration camps, and the involvement of specific countries like France's role in the war. However, it is these key battles and their outcomes that provide a structured narrative capable of encompassing the vast scope of World War II while maintaining a clear focus essential for educational purposes.