After running the command umount /mnt, the following error message is displayed: umount: /mnt:
device is busy. What is a common reason for this message?

A.
The kernel has not finished flushing disk writes to the mounted device.

B.
A user has a file open in the /mnt directory.

C.
The previous rm command has not finished.

D.
The files in /mnt have been scanned and added to the locate database.

E.
The kernel thinks that a process is about to open a file in /mnt for reading.