Question

companies hired pinkertons to
move employees to company towns.
negotiate with unions in the workplace.
force scabs to cross picket lines.
report on and bust unions.

Explanation:

The Pinkertons were a detective agency. Companies hired them to gather information about unions (report on them) and take actions to disrupt or destroy unions (bust unions). Moving employees to company towns was more about company - town establishment rather than Pinkerton's main role. Negotiating with unions was not their typical task as they were more of a force - based entity against unions. Forcing scabs (strikebreakers) to cross picket lines was part of disrupting strikes, but their broader role was reporting and busting unions.

Answer:

report on and bust unions.