According to economist Karl Marx and Friedrich Engel’s publication “The Communist Manifesto”, what was the key to ending the struggle between people of upper and lower classes?

The key to ending the struggle was to walk away from capitalism and embrace communism, a radical form of socialism.

Create a society favorable to the upper classes.

The key to ending the struggle was for everyone to embrace capitalism.

The people of lower and upper classes should unite together to overthrow their governments.