At the most general level, the NLRB holds a union representation election if at least of employees in the bargaining unit sign authorization cards.

30 percent

Explanation:

NLRB is known as National Labor Relations Board. It Is an independent federal agency saddled with the responsibility of making sure workers are well treated. This board helps in negotiation for workers welfare. It helps in electing employee representatives of the union and also the removal of a serving member of the union.

Election is valid if at least 30 percent of employees in the negotiation unit sign authorization cards.

the correct answer is c.