C,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.
同意香香茶的解释,“has allowed”这个动词时态很重要,表明working ten hours是指过去the most productive employees工作的那10个小时,而不是company president要改的制度中所说的10个小时。
因为如果是后者的话,就应该是"Working ten hours a day will allowed the most productive employees to work two hours alone each day in their respective offices relatively undisturbed by fellow employees.”,选项C改成这样才是对president的proposal起到了加强作用,“has allow"是削弱。