Question ID:PT63 S3 Q6 Passage:A transit company's bus drivers are evaluated by supervisors riding with each driver. Drivers complain that this affects their performance, but because the supervisor's presence affects every driver's performance, those drivers performing best with a supervisor aboard will likely also be the best drivers under normal conditions.  Stem:Which one of the following is an assumption on which the argument depends? Correct Answer Choice:DChoice A:There is no effective way of evaluating the bus drivers' performance without having supervisors ride with them. Choice B:The supervisors are excellent judges of a bus driver's performance. Choice C:For most bus drivers, the presence of a supervisor makes their performance slightly worse than it otherwise would be. Choice D:The bus drivers are each affected in roughly the same way and to the same extent by the presence of the supervisor. Choice E:The bus drivers themselves are able to deliver accurate assessments of their driving performance.