The average quality of labor has increased, partly because the demand for education and health care are:
a. income elastic—rising national income generates more than proportional increases in spending on these items
b. income elastic—falling national income generates more than proportional increases in spending on these items
c. income inelastic—rising national income generates more than proportional increases in spending on these items
d. income inelastic—rising national income generates less than proportional increases in spending on these items