What major event has proven most signigicant in changing the course of the 20th century?

I have a history 102 final next week and I was looking for some help from someone who is good at history. The questions is Which of the following six major events has procen most significant in changing the course of the 20th century? Progressive Era Politics, World War I, World War II, Civil Rights, Watergate, or the Cold War. If anyone can help at all that would be great. Thank you in advance.What major event has proven most signigicant in changing the course of the 20th century?If I had to pick, I would say World War II. Just like after WWI, the entire map of Europe got a complete makeover after the war. However, the dropping of the atomic bomb on Japan to this day, and forever will be a huge controversy. Also, the United Nations was formed in reaction to WWII. WWII, more than any other war, also saw the advancement of technology at an incredibly rapid pace. Lastly, the state of Israel was officially established as a result of the Holocaust, and I'm sure you know what that has led to over the past 50 or so years.
What major event has proven most signigicant in changing the course of the 20th century?
In my opinion, it was WWI, and the Treaty of Paris afterward (sometimes mistakenly called %26quot;The Treaty of Versailles,%26quot; which was only one part of the total). First, there was the war, itself and the millions of people it involved, the technology it created or advanced and the conventions that came from the war -- for instance, the convention against using certain weapons like poison gas. The Treaty of Paris created nations that had no existed before -- for instance, Iraq was created by the British from three separate peoples who had little in common with each other. The nation of Israel was created from palestine. Poland became a separate nation, The League of Nations was the precursor to the United Nations, etc.etc -- too much stuff to list here, but believe me, no event in the 20th century changed the world as much.