i picked E but its not the right answer. can someone tell me why?

the answer is b which i don't get because an assumption is unstated and it seems that OA's answer is stated in the premise.


thanks

A company's personnel director surveyed employees about their satisfaction with the company's system for awarding employee performance ratings. the survey data indicated that employees who received high ratings were very satisfied with the system. The personnel director concluded from these data that the company's best performing employees liked the system.

The personnel director's conclusion assumes which of the following?
A) no other performance rating systems is as good as the current system
b) the company's best performing employees received high ratings
c) employees who received low ratings were dissatisfied with the system
d) employees who receive high ratings from a performance rating system will like that system
e) the company's best performing employees were motivated to perform well by the knowledge that they would receive performance ratings.

OA b