The Owner of a Large Tuna Canning Factory Wants to Find

The owner of a large tuna canning factory wants to find ways to make his employees more productive. The owner hires a group of researchers who systematically vary aspects of the work environment (such as the lighting and temperature) and then observe how those changes impact the behavior of the employees. Much to the owner's delight, simple changes such as lowering the temperature and increasing the lighting, improved the productivity of his employees. Which of the following revelations would ca

A) Lowering the temperature improves productivity more than increasing the lighting.
B) These results cannot be generalized to other factories.
C) It is the presence of the researchers, not the environmental changes, which affect productivity.
D) All of the above.