M: The office door was locked when I came back yesterday. I left something important in my office. Why didn't you answer my phone call afterwards? ,F: Maybe it was too noisy to hear it. I thought you would have the key on you.
(A) M: Okay, I see. You thought  I would have the key. Yeah, but I went back to the office because I wanted to get the important things. (B) M: Really? You mean maybe it was too clear to hear it? But I went back to the office because I wanted to get the important things. (C) M: Just a minute! I do not quite follow what you are saying, would you mind repeating that? (D) M: Okay. Actually I left nothing important in my office and  I went back to the office because I wanted to lock the office door.
A