Which of the Following Is an Example of a Union

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

A) Sam, a union member, is threatened by Dan, his boss, with loss of benefits if he votes for a union.
B) Genna, an operations head, threatens to close down a plant if organized by a union.
C) Lillian, a new employee, refuses to join a union.
D) Hill, a nonunion employee, spies on union meetings.
E) Pete, a union representative, makes a contract that requires his employer to hire employees satisfactory to the union.