The Average Workweek in U.S.manufacturing Plants

The average workweek in U.S.manufacturing plants

A) has dropped steadily since 1960 from about 60 hours per week to 35 hours per week currently.
B) has increased from about 35 hours per week in 1970 to about 45 hours per week by 2010.
C) fluctuates significantly over the business cycle, averaging about 50 hours per week at business cycle peaks and 32 hours per week at business cycle troughs.
D) dropped from about 55 hours per week in the early part of the 20th century to approximately 40 hours per week by 1950 and since 1950, aside from small variation over the business cycle, has remained at about 40 hours per week with no trend in either direction.