A. It promoted the overthrow of absolute monarchies. is your best answer
Conservatism affect the nationalist movements in Europe, as the conservationist believed in nationalism, which meant that the people gets the most power. Nationalists used this reason to be able to drastically change their countries government, and create a different national government.
Examples can be found in:
French Revolution:
The French Revolution brought drastic changes (however, did not attain the goal they wanted exactly). They were able to overthrow the monarchy, and set up a new government under Napoleon Bonaparte. However, Bonaparte soon became such like a military dictator, and ruled the French Empire until it collapsed.
American Revolution
The American Revolution was able to liberate the colony located in present-day U.S.A from the British Royal crown. They were able to establish a federal system of government with parts of British government and Ancient Greek government styles infused into their system.
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