During a girl scout picnic, lavinia was randomly selected to be on one baseball team and carla on the opposing team. before the game started, lavinia and carla were each convinced that their own team was the better one. the girls' beliefs best

in group bias

Explanation:

In-group bias: In social psychology, the term in-group bias is also referred to as in-group favoritism, in-group preference, in-group–out-group bias, and intergroup bias.

In-group bias is defined as a phenomenon in which an individual displays a particular pattern of supporting different members of his or her in-group as compared to the out-group people or members. It can be displayed in terms of the evaluation of one person who belongs to a specific group by a member of the other group.

In the question above, the girls' beliefs best illustrates in group-bias.