The river labeled "c" starts in the swiss alps and flows through germany, france, luxembourg, and the netherlands.

Rhine River

Explanation:

The Rhine River is a major European river that begins in Switzerland and flows through Germany and the Netherlands, emptying into the North Sea. It also forms part of the borders of Switzerland, Liechtenstein, Austria, Germany and France. The river was vital for both the Roman Empire and the Holy Roman Empire. It is also a symbol of German nationalism.

both include an amendment process.

julius caesar turned the roman republic into the roman empire by coming in and taking the "dictator" role during the time of a civil war (elites vs lower classes) winning battles and reputation, then declaring him dictator for life

hope this : )