In Which of the Following Situations Is Third-Party Intervention Appropriate

In which of the following situations is third-party intervention appropriate?

A) A couple who disagrees over the custody of their child, yet doesn't want a judge to have the final say.
B) Members of two different fraternities are being destructive to one another's property.
C) Two girls are fighting over a doll and, unexpectedly, the doll is ripped in half.
D) Co-workers they are being paid drastically different salaries for the same job.
E) All of the above