Which of the following statements is TRUE of certification of a union by the NLRB using a secret-ballot election?

a. Once a union is certified by the NLRB, its status is binding on the employer for at least two years, during which time the employer must bargain with it.

b. It is mandatory for a certified union to undergo a recertification election every two years.

c. If a certified union fails to reach its first contract within two months of bargaining, it is penalized under the NLRA.

d. The NLRB will not entertain a rival certification petition for a bargaining unit represented by a certified union within the first year.