I hope that these questions were from the author's memory and not worded exactly as typed. Because the questions used for first round filtering of interview candidates should be clear cut and not open to interpretation.

Namely, question 14 is odd,

    What Signal does a child send to a parent when it is finished.

The child doesn't send signals in this event, the kernel sends signals to the parent when the child's state changes, and one of those states is the child exiting. Although, the default action of SIGCHLD is ignore, and can a signal that is ignored be considered to be sent at all?