What Are the Conclusions of Research Examining the Effects of an Examiner's

What are the conclusions of research examining the effects of an examiner's race on examinee's performance?

A) there may be significant bias, but it depends on the race of the examiner and examinee
B) race and socioeconomic status combined show higher rates of bias
C) there appears to be significant bias, and this should be taken into consideration for assessment administration protocol
D) there is no conclusive evidence about the effect of examiners' race on examinees' performance