Jacinda failed her last history midterm. Which of the following conclusions would be most representative of a self-serving bias on Jacinda's part?

A) "I really didn't prepare well enough for that test."
B) "I wasn't concentrating as hard as I should have during the test."
C) "I lack ability in history."
D) "I think the test questions were ambiguous and confusing."

Self-serving bias is a common type of cognitive bias that involves attributing successes to internal or personal factors while attributing failures to external factors. In this case, choice D ("I think the test questions were ambiguous and confusing.") is an example of self-serving bias because Jacinda is attributing her failure not to her own lack of preparation or ability, but to the external factor of the test questions being poorly designed.