Final answer:
At the Congress of Vienna, Klemens von Metternich feared nationalism and liberal movements. He aimed to prevent the breakup of the Austrian Empire and maintain the balance of power by suppressing these movements. Option C is correct.
Step-by-step explanation:
At the Congress of Vienna, Klemens von Metternich's greatest fear for the future of his country was nationalismand liberal movements.
After the Napoleonic Wars, Metternich and other conservative leaders sought to maintain a favorable balance of power and prevent future revolutions.
They aimed to establish conservative political regimes and suppress nationalist and liberal movements that threatened the stability of their countries.
Metternich specifically feared the rise of nationalism and the potential breakup of the Austrian Empire due to aspirations for independence among various ethnic groups within the empire.
Hence, option C is correct.