Which one of the following is an ethical obligation of a mentor as opposed to a challenge that mentoring relationships might pose to mentors?

Being aware of important issues in students' lives without prying.
Taking care to avoid favoring one’s own students.
Avoiding abuse of the power afforded mentors through students’
      dependence on them for educational, financial, and emotional
      support.
Balancing oversight and independence so as not to over-direct
       students.