In the United States, the Quality of Labor Has Been

In the United States, the quality of labor has been increasing, based on evidence that over time

A) the percentage of the adult population that has had 4 years or more of college has been decreasing.
B) the percentage of the adult population that has had some high school has been increasing.
C) the percentage of the adult population that has completed high school has been decreasing.
D) a larger percentage of the adult population has completed high school or 4 years or more of college.