Which of the Following Best Defines the Preferential Shop Form

Which of the following best defines the preferential shop form of union security?

A) A company can hire nonunion people, but they must then join the union.
B) A company can hire only current union members.
C) Employees who do not belong to the union must still pay dues.
D) A company gives hiring advantages to union members.
E) Union members must maintain membership for the contract period.