Why Was There a Slowdown in Productivity Growth in the 1970s

Why was there a slowdown in productivity growth in the 1970s?

A) Workers had less capital to work with than in previous decades.
B) The labor force engaged in less education and training in the 1970s.
C) The energy price increases caused research efforts to be directed at saving energy rather than increasing productivity.
D) The oil crisis in the 1970s decreased aggregate demand.