A transit company's bus drivers are evaluated by supervisors riding with each driver. Drivers complain that this aff...

Annie on November 19, 2019

Hi @nivensdc,

Here's a breakdown of the argument:
Premise: Bus drivers are evaluated by supervisors riding with the drivers.
Premise: Drivers complain that the supervisors presence affects their performance.
Premise: Supervisor's presence affects every drivers performance.
Conclusion: Those performing best with a supervisor present, will likely be the best under normal conditions too.

You're looking for a premise which MUST BE TRUE in order for the conclusion to be correct.

Answer Choices:
(C) is incorrect for a few reasons. First, it mentions "most" drivers, while the conclusion is about all drivers. Therefore, it doesn't necessarily support the conclusion. Second, the argument does not tell us about how drivers are under normal conditions, which is the point of the conclusion.

(D) is correct. This answer choice fills a gap in the logic above. Premise three tells us that supervisors affect driver performance, and the conclusion finds that those who do best with a supervisor in the bus will do best without them there. This assumes that all drivers get the same level of nervous in front of the supervisors. This is a big assumption to make about people, as we don't all get the same about of stage fright before performing in front of others. This answer choice fills this gap in the logic, and is required for the conclusion to be correct.