Why is question D correct?

Hi, I read the explanation already provided to user Shiyi, however, I thought that the explanation of a presiding judge's duty toward minimizing juror inferential error was an indicator that judges are already trained in this tendency, and therefor, specific training alone would not be sufficient. Rather, the training should incorporate cognitive research from psychologists. It doesn't seem that answer D appropriately states the nature of training that would be necessary to make this answer correct.