There Is Little Substantial Upward Mobility in the United States

There is little substantial upward mobility in the United States.One primary reason is that the tools used for upward mobility,such as education,are no longer as effective as they once were.What is the second primary reason,according to the text?

A) An increasing number of women with children work outside the home.
B) The U.S.tax structure favors rich families passing on their wealth to their heirs.
C) The poverty rate continues to climb for Blacks and Hispanics.
D) Government programs have a built-in disincentive for work.