During a Union Organizing Campaign, Which of the Following Requirements

During a union organizing campaign, which of the following requirements must be fulfilled to qualify for an NLRB-sponsored election?

A) The employer must request the NLRB to conduct the election.
B) There should be more than 1000 employees in the bargaining unit.
C) 30 percent of the workforce should sign authorization cards.
D) The employer must prove that the union organizers are engaging in unfair labor practices.