Over the Past Ten Years,more Than 50 Percent of the Promotions

Over the past ten years,more than 50 percent of the promotions to partner at the law firm of Smithers and Johnson have been given to women.This trend could be explained by

A) the firm's realization that women would improve the quality of the legal service provided by the firm.
B) affirmative action legislation.
C) an increase in the number of female lawyers graduating from law school.
D) the increased number of women in the labor force.
E) All of these choices