what did factory owners do to prevent unions from forming?\nthey paid off union leaders so they would stay…

Brief Explanations:

Factory owners historically used various anti - union tactics. Paying off union leaders was one such unethical method to keep them away and disrupt union formation. Having union leaders arrested without cause was also a common illegal practice to intimidate the union movement. Hiring only workers who promised not to join a union was another way to prevent unionization. Using force to end union activities, such as hiring strikebreakers or private security to attack union members, was also prevalent.

Answer:

All of the above options describe actions that factory owners took to prevent unions from forming. So the answer could be considered as all of the options presented (They paid off union leaders so they would stay away; They had union leaders arrested for no cause; They only hired workers who promised they would not join a union; They used force to end union activities).