<em>D. Preventing future warfare.</em>
Explanation:
After World War I, the League of Nations was created with the goal of peace and to not start another war.
The League of Nations was thought up by President Woodrow Wilson, who was big on peace and making amends across the nation. He came up with the League of Nations in order to try to maintain the peace after World War I and to prevent future disputes from happening. Numerous countries joined the League of Nations, but despite the President of the United States, Woodrow Wilson, being so involved in it, the United States never officially joined the League of Nations because some individuals in Congress deemed it useless and unnecessary.
They weren't wrong either... the League of Nations was weak and did not have any real power to deal with disputes that would happen. The League did not have any of their own troops and their representation was often messy, which did more harm than good sometimes. When disputes did happen, the League of Nations took too long to respond and things would get out of hand way too fast for them to deal with.
Eventually, the League of Nations was abolished. A lot of citizens felt it was useless and did not hold any real power. Most of the time, during crucial situations, the League did not pull through properly.
