When Darren's classmate earns a D on an essay for their history class, Darren figures the classmate is unmotivated and should have spent more time working on the paper and less time socializing. The classmate is disappointed with her grade, but she knows she didn't have much time to work on the essay because she had to work double shifts the entire week before the paper was due. The different attributions for the low grade on the essay illustrate

a. the actor-observer bias.
b. defensive attributions.
c. the self-serving bias.
d. cognitive dissonance.