Which of the Following Is Not an Unfair Labor Practice

Which of the following is not an unfair labor practice by a union:

A) refusing to bargain with employers about wages and working conditions
B) engaging in secondary boycotts
C) ordering workers to go on strike when a collective bargaining agreement is not reached
D) including in a collective bargaining agreement a term that requires the employer to pay a union leader a salary even though the leader does no work for the company
E) all of the other choices are legal activities