What happened after the student said she had turned in her assignment but the teacher must have lost it?

Choices:
A. the student admitted to bringing the assignment
B. the teacher said open your sent folder
C. not enough information
D. the student explained that she deletes her assignment
the teacher said open your sent folder
I do not fully understand exactly what you are asking so I will restate what I believe you are asking and then I will answer it. What was the best excuse that a student ever gave for having failed to do something? I would have to say that I was most entertained by a student’s response to “Why are you late for school?” The student said, “I awoke in time this morning but there was a mouse sitting on the edge of my bed. I looked at him and he looked back. The mouse said to me, ‘Go back to sleep’ and what could I do? He had a gun.”
The following has worked a few times too when students refuse to talk. That is, I know that one of the assembled students was the culprit for some activity. When they will not talk, I interview them one at a time while the others are kept away from each other. Then when they are assembled before me again, I say, “Thank you gentlemen. I know who did it so you others are free to return to class.” All but one arises and leaves. This works more times than not.
For years I have given assignments via email and I have collected assignments via email. Nothing has ever gotten lost this way and things are timestamped. I do not have to make photocopies and even students who are not present the day that the assignment is announced in class, get the assignment in a timely manner. One young lady told me, “I turned it in but you must have lost it.” “Okay,” I said, “Open your sent folder and show me that you sent it.” She replied by saying, “I delete my sent folder to keep from clogging up my email.” I told her that I understood and that she could show me an empty sent folder to prove that she was telling the truth. She said, “I lied.”