Which of the following statements best describes income distribution in the United States?
a. The richest 20 percent of the population has about 20 percent of the national income.
b. The richest 20 percent of the population has a much greater share of income than the poorest 20 percent.
c. Most people earn the same income.
d. The richest 20 percent of the population has slightly more income than the poorest 20 percent.