Final answer:
Under the Taft-Hartley Act, individuals with the authority to hire, fire, assign, or discipline are typically considered 'employers'.
Step-by-step explanation:
The Taft-Hartley Act, passed by Congress over President Truman's veto in 1947, restricted many of the powers of labor unions. One aspect of the Taft-Hartley Act addresses the roles individuals play in a work setting, particularly those with the power to hire, fire, assign, or discipline, and although the Act itself does not explicitly define these people with the terms from the question choices, within the context of labor relations these individuals are commonly considered to fall into the category of an 'employer'. As such, according to the functions laid out, the correct answer to the student's question would be option 1) Employer.