What major world event occurred from 1939 to 1945?

The period from 1939 to 1945 is recognized as World War II, a significant global conflict that involved most of the world's nations. This war was marked by the large-scale mobilization of countries and their populations, widespread battles across Europe, Asia, Africa, and the Pacific, and the introduction of total warfare, which included the use of nuclear weapons towards the end of the conflict.

World War II was characterized by the struggle between the Allied Powers, including the United States, the United Kingdom, the Soviet Union, and China, against the Axis Powers, primarily Nazi Germany, Imperial Japan, and Fascist Italy. Key events during this period include the invasion of Poland by Germany in 1939, the attack on Pearl Harbor in 1941, and the eventual defeat of Axis powers by 1945, culminating in significant geopolitical changes worldwide.

The other options highlight significant historical events but do not align with the specified timeframe. World War I took place from 1914 to 1918, the Great Depression occurred in the 1930s, and the Cold War began after World War II, approximately in the late 1940s. Hence, World War II is the correct answer for the major event that occurred between 193