【单选题】During the first 70 years of the 20th century, inequality declined and Americans prospered together. Over the last 30 years, by contrast, the United States developed the most unequal distribution of i...
A.
The wage movements in the U.S. are dominated by swings in the demand for education-related skills.
B.
The American educational system is what made American the richest nation in the world.
C.
Technology raced ahead of education in the first half of the 20th century.
D.
American high school graduation rates leveled off at 80 percent in 1970.