What was the relationship between nationalism and revolutions in Europe and the Americas during the 19th century?
A. Nationalist revolutionaries embraced the concept of popular
sovereignty to call for an end to absolute monarchies.
B. Nationalist leaders convinced revolutionaries to attack republican
governments that were viewed as too weak.
C. Nationalist governments began to oppress minority groups and
provoked them to demand political independence.
D. Nationalist principles were based on Enlightenment ideas and
inspired revolutionaries to embrace nonviolent protest.

A.  Nationalist revolutionaries embraced the concept of popular  sovereignty to call for an end to absolute monarchies.

Explanation:

During the peak era of nationalism, most countries in the world adopted a monarchy system. This system gave a single king as the absolute ruler who can do anything within the government body. Sometimes, these kings do this at the expense of the people.

Revolutionaries realized how corrupt this system is.

They adopted the idea from the enlighten thinkers who promoted a concept of government that enable the people to influence the government. This concept is called popular sovereignty.  They forcefully remove the nobles from their power and establish democracy as a new system of government.