Alphonse Failed His Geology Midterm

Alphonse failed his geology midterm. According to Weiner's attributional model, if Alphonse makes an external-unstable attribution for his failure, he is MOST likely to say,

A) "It was just bad luck that most of the exam was on the one chapter I didn't study."
B) "I was really tired during the exam because I had to work the late shift the night before the exam."
C) "I just can't seem to catch on in my geology classes, and I don't think I'll ever learn all those terms."
D) "That professor has impossible exams; if I retake the class with a different professor, I'll probably do much better."