Which of the Following Is an Example of a Union

Which of the following is an example of a union unfair labor practice?

A) Ned refuses to reinstate workers when job openings occur because the workers participated in a lawful strike.
B) Gill, an operations head, threatens to close down a plant if organized by a union.
C) Jon, a new employee, refuses to join a union.
D) Pat, a nonunion employee, spies on union meetings.
E) Oliver, a union head, forces an employer to stop doing business with another employer who refused to recognize the union.