Between about 1960 and 1990 the wage ratio was constant at about 60 % although women's human capital was increasing along several dimensions. What is the most likely explanation for this paradox?
a. Reservation wages were falling over the period, drawing less-skilled women into the market
b. The increase in education did not translate to skills that were valued in the market
c. There was a massive rise in discrimination over the period.
d. Affirmative action laws caused considerable harm to women in the labor market.
e. The data were only from biblical times