During the struggle for italian unification, the “red shirts” were forces made up of
a. anarchists.
b. nationalists.
c. socialists.
d. monarchists.

During the struggle for Italian unification, the “Red Shirts” were forces made up of "B. nationalists," although it should be noted that not all nationalists referred to themselves this way. 

Iwould say a, due to the fact these routes display many things that would be useful and provide explanations for how states are known.