Which of the Following Has Been Shown to Reduce the Personal/group

Which of the following has been shown to reduce the personal/group discrimination discrepancy?

A) Ask people to consider the experiences of their group members on a case-by-case basis.
B) Make clear that one's own experiences should be compared to other members of one's group rather than another groups' members.
C) Emphasize that the discriminatory acts under consideration are minor and infrequent.
D) All of the above will reduce the PGDD.