The violent union strikes in the 1890's reinforce the belief that labor union members were

This sentence can be finished with different adjectives, all of them with a negative connotation. "Violent" is the one that summarizes the idea the most.

In the 1890s violent strikes happened in the whole country, in small towns and big cities. It does not matter the origins, most of the workers responded with the same ferocity when the Unions were attacked. An big amount of workers an civilians died during this decade.

bismarck believed in using force

is the correct answer!