Answer:
the Enlightenment
Metternich's initiatives to curb nationalism
sweep of revolutions across Europe
formation of the kingdom of Italy
Step-by-step explanation:
Historians estimate that the Enlightenment started most likely in 1715.
It wasn't until 1773 that Metternich was born. His opposition to nationalism is considered one of the things that caused the unification of Germany and Prussia instead of Austria.
The sweep of revolutions began in 1848 (that year was when Metternich left his position of power).
The Kingdom of Italy was founded in 1861.