A. Draw the nation into unnecessary conflicts.
Step-by-step explanation:
In 1920, the United States Senate rejected the Treaty of Versailles, the peace treaty that ended World War I and created the League of Nations, due to fears that the League of Nations would draw the nation into unnecessary conflicts.
President Woodrow Wilson was the one who thought of the League of Nations, which was talked about in his Fourteen Points. His Fourteen Points were plans for during and after World War I and mostly had to do with peace and preventing future conflicts. The League of Nations ended up being part of the Treaty of Versailles, but even though United States President Woodrow Wilson came up with the League of Nations, the United States never ended up joining it.
This was because many people were isolationists after World War I. Isolationists did not want anything to do with foreign affairs, as they feared it would draw the nation into unnecessary conflicts. Many people did not want a repeat of World War I and essentially wanted to protect their country. The United States Senate was also filled with isolationists and wanted nothing to do with foreign problems, so they simply did not want to join the League of Nations.