Which international agreement is known for ending World War I and redrawing many national boundaries in Europe?

The Treaty of Versailles is recognized as the primary international agreement that officially concluded World War I in 1919. This treaty not only brought hostilities to an end but also instituted significant territorial changes across Europe. The treaty imposed reparations on Germany, altered national borders, and dissolved empires such as the Austro-Hungarian and Ottoman Empires, leading to the creation of new nations and redrawing boundaries.

In contrast, other agreements and treaties mentioned in the options serve different historical contexts. The Paris Peace Accords, for instance, are linked to the end of the Vietnam War in 1973, while the Montreal Protocol is a modern environmental agreement aimed at protecting the ozone layer, and the Treaty of Westphalia, signed in 1648, is credited with helping to establish state sovereignty and the modern system of international relations, but it is not related to World War I. Thus, the Treaty of Versailles is the key instrument that not only ended the war but also fundamentally reshaped the map of Europe.