It is difficult for most supervisors to avoid bias when evaluating their subordinates, mainly because many of the tools lead to rater errors like the halo effect, which can best be defined as:

A. Rating someone based on her education or position B. Giving someone an average rating because the supervisor is unsure of the actual performance C. Rating someone based on his most recent positive behavior, not his overall performance D. Giving someone a high rating because she is popular with her peers