Which of the following regarding the importance of education to our national economy is a true statement?

Group of answer choices

A. education has historically been the smallest public function in the United States.

B. the percentage of Gross Domestic Product used for education has been fairly consistent since 1970.

C. approximately 15 percent of the U.S. Gross Domestic Product goes toward all education institutions.

D. approximately 25 percent of the population of the United States is involved to some degree in education.