Susan usually does well on her written assignments and she says this is because she works really hard. but when she gets a bad grade on her last written assignment, she says it is because the teacher does not like her. her explanations show that she is making a:
a. reflected appraisal.
b. better-than-average effect.
c. self-serving bias.
d. downward comparison.

(C) Self-serving bias

Explanation:

 The self serving bias is one of the type of cognitive process in which it enhanced the self esteem and also it refers to the people tendency for attribute in the different types of positive events by using the external factors.

According to the given question, the Susan is usually used for writing the assignments and her explanations describe about the self serving bias.

The self serving bias is one of the concept that explain about both the external and the internal situational forces in the environment.

 Therefore, Option (C) is correct.