What were the main characteristics of the post-Vienna political system of Europe?
1. Initially, at the Congress of Vienna, the fundamentals of peace were determined by agreement among the four major powers, be it the Holy or Quadruple Alliance. These were Austria, Britain, Russia, and Prussia. In 1818, France was also granted a great power status and accepted into the European Concert.
2. The Napoleonic map was redesigned as much as possible to pre-1789 borders by the dissolution of Napoleonic states and the restoration of European monarchies. No state was to be reformed in a nationalistic fashion.
3. Monarchism, anti-nationalism, and antiliberalism were the main fundamentals of the post-Vienna peace, while wars of conquest within Europe were now assumed to be a hostile action by the major actors and the great powers now countered the aggressive use of force to redraw borders. If war became inevitable with the failure of diplomacy, any power would first have to collectively to quarantine the belligerent power with the other Concert members.
4. The major powers agreed to reconcile matters among themselves rather than take individual action. Diplomacy was always to take precedence over the use of force, a last resort.
5. Preserving the peace by acting in concert became the major powers’ common goal, for which diplomacy became an effective instrument of action.
6. Among the great powers, Austria stood out as both the organizer and balancer of the system.

According to these, the correct answer is option D.