Why Would a Wage Differential Due to Discrimination Be Unlikely

Why would a wage differential due to discrimination be unlikely to persist in a competitive labor market? (i) Workers who are victims of discrimination will eventually drop out of the labor market.
(ii) Competing firms will hire more of the workers who are temporarily victimized by discrimination.
(iii) There is a cost advantage for firms that do not discriminate.

A) (i) and (ii)
B) (ii) and (iii)
C) (i) and (iii)
D) (i) , (ii) , and (iii)