Three Students Form a Study Group for Their Social Psychology

Three students form a study group for their social psychology course. Which of the following possibilities would be the best indication than the group is experiencing biased sampling?

A) The students focus on the information they all already know instead of reviewing the unique knowledge that each person brings to the group.
B) The students assign specific roles and tasks to each other.
C) In the effort to categorize themselves as "good" group members, the students conform to each other's opinions about the quality of the course instruction thus far.
D) The students refuse to utilize the strategy of brainstorming.