Kelly, a Republican, and Carlos, a Democrat, both believe that members of their own political party are more fair-minded and trustworthy than members of other parties. Their beliefs best illustrate:

A. the just world phenomenon

B. ingroup bias

C. the social responsibility norm

D. deindividuation

B. ingroup bias

Explanation:

Ingroup bias: The term 'ingroup bias' refers to the propensity of an individual to choose or favor his or her group over the other group. The ingroup bias can affect or influence both the group's and individual's behavior to an extent.

In other words, the ingroup bias refers to a group in which specific persons are identified as a part of or belong to the group.

Example: Nationalities, social classes, races, etc.

In the question above, the beliefs are best illustrated in terms of ingroup bias.