A:Group is a team that three or more than three people who realize benefits from each other and work together to achieve the same goal.

B:Detail characteristics of the groups is interdependence, common goal, group personality, commitment,cohesiveness, group conflict, social facilitation, gender differences, group size and norms.

C: Make sure that the group has reasonable number.

Every member depends on each other that we should take the lead in the discussion.

We should make sure that members have a common goal that they willing to stick together.

We should encourage reasonable conflict that all of the members aren't afraid to give their opinions.