Answer: It's all my fault. I overslept. I'm really sorry.
Explanation: You’ve arrived half an hour late to pick up a friend. She was scheduled to take an examination, and even if you speed on the way to the university, she will now lose at least twenty minutes of the time she needs to complete the exam. According to the authors, the best thing to say when you arrive is it’s all my fault. I overslept. I’m really sorry.
