Final answer:
Henry C. Frick made the decision to call in the Pinkerton detectives during the Homestead strike at the Carnegie Steel Company, supported by the anticipation of plant managers.
Step-by-step explanation:
The decision to call in the Pinkerton detectives during the labor strikes was made by the management of the striking companies, often with the support of local or national authorities. At the Homestead factory of the Carnegie Steel Company, it was plant manager Henry C. Frick who ordered a lockout and hired the Pinkertons to deal with the strike.
In the case of the steel mill owned by Andrew Carnegie in Homestead, managers anticipated the workers' strike and contracted with the Pinkerton agency to protect the factory and its replacement workers.