What Did the Hawthorne Studies Reveal About Worker Motivation

What did the Hawthorne Studies reveal about worker motivation?

A) That the atmosphere of a work group and participative supervision affect the degree of productivity
B) That the laissez-faire management style is most effective
C) That a substantial percentage of the workforce will engage in acts that are discordant with their personal values systems if offered enough compensation
D) That workers have a ceiling to their productivity - once their basic needs are met their productivity begins to wane