Question

the best example of cause and effect after the congress of vienna is
napoleon was defeated, so france started a revolution.
austria won territory in italy, so italy adopted austrian customs.
spain became a monarchy, so the french empire was weakened.
the french empire was demolished, so liberal ideology grew.

Explanation:

After the Congress of Vienna, the French Empire was demolished. This led to the growth of liberal ideology as people started to question the old - order (monarchies and conservative rule).

• For the first option: Napoleon's defeat was before the Congress of Vienna, and the French Revolution was earlier (1789 - 1799), while the Congress of Vienna was in 1814 - 1815.
• For the second option: Austria's acquisition of Italian territory did not directly cause Italy to adopt Austrian customs. There was more of a political subjugation rather than a cultural adoption in a cause - effect sense as described.
• For the third option: Spain becoming a monarchy (restoring the Bourbon monarchy) was a result of the Congress of Vienna's aim to restore old - order monarchies, but it had no direct cause - effect relationship with weakening the French Empire (which was already defeated).

Answer:

the French empire was demolished, so liberal ideology grew.