From 1990 to 1997 in the United States, the number of working men grew by 6.7 percent; the number of working women grew by 11 percent. During this time, average wages for men grew by 20 percent, whereas average wages for women grew by 25 percent. Which of the following two explanations seems more consistent with the data?
a. Women decided to work more, raising their relative supply (relative to men).
b. Discrimination against women declined, raising the relative (to men) demand for female workers.