In the early 2000s, analysts feared that low academic achievement in math in the United States may reduce U.S. economic growth by as much as half a percentage point a year. "That drag will become increasingly apparent…as other countries dismantle regulatory obstacles and alter tax laws that put them at a disadvantage." In terms of sources of growth, the quotation suggests that some other countries are currently at a disadvantage because of:

A. social capital.

B. human capital.

C. growth-compatible institutions.

D. technology.