Given that employees of the XYZ Company could, in theory, do their work at home, the company developed a radical plan to increase efficiency: eliminate office-space expenditures by having employees work at home. To evaluate this plan, XYZ' s managers asked volunteers from the company' s staff to try the arrangement for six months. There were several volunteers; significantly, their productivity during this period was as high as or higher than before. Which of the following, if true, would argue most strongly against deciding, on the basis of the trial results, to implement the company's plan? ["The employees who agreed to participate in the test of the plan were among the company's most self-motivated and independent workers.", 'The volunteers who worked at home were able to communicate with other employees as necessary for performing the work.', 'The savings that would accrue from reduced office-space expenditures alone would be sufficient to justify implementation of the plan apart from any productivity increases.', 'Minor changes in the way office work is organized at XYZ would yield increases in employee productivity similar to those achieved in the trial.']