In the U.S. labor market, _____.

a. the supply of highly-educated workers has increased at a higher rate than the supply of less-educated workers

b. computers have decreased the demand for low-skilled workers and increased the demand for highly-skilled workers

c. technological changes have benefited workers with low level of skills

d. the distribution of income based on labor productivity has increased the supply of low-skilled workers

e. the supply of highly-educated workers has increased at a higher rate than the demand for highly-educated workers