After Running the Command Umount /Mnt, the Following Error Message

Multiple Choice

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) Another file system still contains a symlink to a file inside /mnt.
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.