Advik, a 15-year-old, believes that the winning team in the intra-school quiz competition won because the members knew the answers to the quiz questions beforehand. He convinces himself that they performed better than his team because they cheated. In the context of the cognitive sources of prejudice, Advik's belief illustrates

a group-serving bias    

Explanation:

Group-serving bias: In psychology, the term "group-serving bias" is described as the human propensity to continuously attribute a specific group's successes towards the groups' own efforts, and therefore attributes failures to some outside interference. However, it can be seen in various ethnic groups, families, etc.

In the question above, Advik's belief illustrates a group-serving bias as he claims the won on the wisdom of the members of his groups.

the correct answer on edgen is:

(c.) prevent the spread of communism.

i just took the test.