Final answer:
The student's lack of concern about the exam stems from their cognitive appraisal of the situation, recognizing that their overall success in the course won't be jeopardized by one failing grade.
Step-by-step explanation:
The student's adaptation response to stress is most accurately reflected in choice C: The student's cognitive appraisal of the situation. The student has maintained an A average throughout the course and believes that even a failing grade on the upcoming exam would not impede the completion of the course with success. This belief likely comes from a strong sense of self-efficacy and the application of secondary appraisals, evaluating the available coping options and their effectiveness to deal with potential stressors.