I'm not 100% sure but it could be: Voluntary Exchange takes place between buyers and sellers:
(btw I copied and pasted from the question so I didn't take any content :D)
Answer:
The Holy Roman Empire faced many territorial challenges.
Explanation:
The first challenge was in Italy: the Italian states that were part of the Holy Roman Empire were separated from the German hinterland by the Alps, which imposed a communication barrier that made it very difficult for Emperors to hold control over these lands.
In what is now Germany, there were also territorial issues. The land was divided among countless states: duchies, counties, princedoms, fiefdoms, city-states, and so on, something that made coordination at the imperial level very difficult.
As centuries passed, the Holy Roman Empire lost control over several possessions: it lost most of the Low Countries, and the Italian city-states like the Duchy of Milan and the Republic of Venice became fully independent.
The Ten-Percent Plan: Lincoln's blueprint for Reconstruction included the Ten-Percent Plan,which specified that a southern state could be readmitted into the Union once 10 percent of its voters (from the voter rolls for the election of 1860) swore an oath of allegiance to the Union.
If you want good sources go to wikipedia and look at the sources used in the wikipedia article. DO NOT USE THE WIKIPEDIA ARTICLE ITSELF AS A SOURCE!