The likely reason that this type of measure will improve the appraisal is:?

To improve performance appraisals an employer might measure the number of people served per hour in a restaurant for example.      

A)    it is an objective measure of performance.        B)    it is a360-degree feedback mechanism.        C)    managers always need to be trained in providing this type of feedback.        D)    All of the above are reasons it will improve the appraisal.