GWD 6-21,请指教

An overwhelming proportion of the most productive employees at SaleCo’s regional offices work not eight hours a day, five days a week, as do other SaleCo employees, but rather ten hours a day, four days a week, with Friday off.  Noting this phenomenon, SaleCo’s president plans to increase overall productivity by keeping the offices closed on Fridays and having all employees work the same schedule—ten hours a day, four days a week.

Which of the following, if true, provides the most reason to doubt that the president’s plan, if implemented, will achieve its stated purpose?

1. Typically, a SaleCo employee’s least productive hours in the workplace are the early afternoon hours.

2. None of the employees who work four days a week had volunteered to work that schedule, but all were assigned to it by their supervisors.

3. Working ten hours a day has allowed the most productive employees to work two hours alone each day in their respective offices relatively undisturbed by fellow employees.

4. Employees at SaleCo are compensated not on the basis of how many hours a week they work but on the basis of how productive they are during the hours they are at work.

5. Those SaleCo employees who have a four-day workweek do not take any of their office work to do at home on Fridays.

答案是C,可以看出ABDE都是无关的可以排除，但是我的问题是C怎么能削弱呢？想了半天也想不通。请NN指点。

非NN

这样想的　公司看到高效员工是十小时四天, 准备让所有人十小时四天, 但如果原来高效员工的牛是牛在在额外的两小时内没人打扰, 那让所有人都十小时就达不到这个目的了．

另外置顶的讨论里有联接方便查

对d有一些疑问，我觉得d也是能引起doubt的，只不过doubt的程度不如c，不知道nn们怎么看？因为d说职工们的薪水只与productive有关，与工作时间无关，所以改变工作时间不能对职工有吸引力，因此也不能增加productive。

不知道这样想对不对，有点绕进去了，各位给盏明灯啊？