The Contribution of Improved Productivity to the Rate of Growth

The contribution of improved productivity to the rate of growth of the U.S. economy

A) historically dominated the contribution of labor and capital, but never by as much as it has in the 1980s.
B) declined during the 1970s but rebounded during the economic periods of the 1980s and 1990s.
C) had been increasing slowly for 10 years when it suddenly fell below zero in response to the recession of 1981-1982.
D) has never been as important as it is in the rest of the world.
E) none of the above.