Which defense mechanism is being used when a student blames their failing a test ont he poor teaching skills of the instructor rather than the fact that they didn't study?

I believe the answer is: Regression

In psychology, regression refers to a situation when people choose to stubbornly hold on to their ego rather than handling an unacceptable result in an objective way. This type of defense mechanism is characterized by childlike behavior which make people resort to blaming, or violence when handed the outcome that dissatisfy them,