Final answer:
The basis for wage discrimination against women was the dubious claim that they were biologically incapable of performing the same jobs as men. Despite this, laws against discrimination have led to a reduced gender wage gap when factoring in comparable education, experience, and expertise.
Step-by-step explanation:
The dubious claim which was the basis for wage discrimination against women is A. Women were biologically incapable of performing the same jobs as men. Wage discrimination has historically been justified through various unfounded biases and stereotypes, including the belief that women were less capable than men due to biological differences. Across the labor market, gender discrimination occurs when women are paid less than men despite identical educational achievement, experience, and expertise. This is especially noteworthy in cases such as the sex-discrimination suit brought against Wal-Mart, demonstrating the importance of comparable productivity characteristics in analyzing fair compensation.
Laws against discrimination and ongoing societal changes have worked towards reducing the gender wage gap. In light of a 2007 Department of Labor study which found that, when controlled for education, work experience, and occupation, the gender wage gap was reduced to only around 5%, it's clear that progress has been made, though challenges remain.