The best explanation of the political role of the U.S. during World War I is:
Although the U.S. joined the war late, it played an influential role in the peace process.
The U.S. entered the war in 1917 and contributed to the final stages of the conflict, but its most significant impact was in shaping the post-war peace, particularly through President Woodrow Wilson's Fourteen Points and the Treaty of Versailles.