Answer :
Final answer:
The nation-state concept became widely used for the first time in D) Western Europe during the Age of Enlightenment and into the 19th century during the rise of nationalism.
Explanation:
The first widespread use of the nation-state concept is considered to have been in D) Western Europe. This began during the Renaissance and later took consolidation during the Age of Enlightenment, flowing into the 19th century with the rise of nationalism. In this period, countries like France and England transitioned from feudal systems to centralised governments, thereby forming the basis of the nation-state system that we know today.
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