Final answer:
Dirk is most likely to explain his calculus exam results as being due to various factors, including lack of preparation and difficulty of the exam.
Step-by-step explanation:
When Dirk fails his calculus exam, he is most likely to explain the results as being due to a variety of factors such as lack of preparation, difficulty of the exam, or even blaming the teacher for not teaching effectively. However, it is important to note that personal responsibility is a key factor in academic success and blaming external factors may hinder growth and improvement.