Which of the Following Statements Holds True for Bargaining Between

Which of the following statements holds true for bargaining between an employer and the union concerning a mandatory subject of bargaining?

A) In-plant food and related services are not compulsory bargaining issues.
B) Wages are compulsory subjects, while bonuses are not.
C) Courts tend to defer to the NLRB in classifying collective bargaining subjects.
D) Under no circumstances can parties take steps that are against best interests of the other party.
E) Neither the employer nor the union must make concessions to the other.