What Was the Result of the Hawthorne Studies That Puzzled

What was the result of the Hawthorne studies that puzzled the researchers?

A) The redesigned jobs made the work easier and faster for the employees.
B) Worker productivity increased when pay was increased.
C) Productivity went up when the amount of lighting was increased.
D) The differential percent pay system was ineffective in increasing productivity.
E) Increased lighting levels improved productivity, but so did lowering lighting levels.