The correct answer is (c)speaking out against World War I
The act made those who spoke against participation in the World War seem like spies who were doing it out of the desire to actually help the Germans. This was in part because many of the people in the US were of German national heritage so there was a lot of fear that there were spies who supported Germany in secrecy. The people would be charged with things like espionage or treason or similar and be put to trial.