Which river forms part of the border between Germany and Poland?

The Oder River forms a significant portion of the border between Germany and Poland. It stretches approximately 854 kilometers, with a notable stretch serving as the international boundary between the two countries. This river is important not only politically, as it delineates national borders, but also economically, as it is a vital waterway for trade and transportation in the region.

The other rivers listed do not share a border with Poland. The Rhone flows through southeastern France and into the Mediterranean Sea, while the Seine runs through Paris and meets the English Channel. The Elbe, although flowing through Germany and eventually reaching the North Sea, does not form a border with Poland. Thus, the Oder’s geographic position and role in separating these two nations make it the correct answer.