What is the term for unmounting a filesystem, which cleans up all references to the filesystem, as soon as it is not in use any longer?

What is the term for unmounting a filesystem, which cleans up all references to the filesystem, as
soon as it is not in use any longer?

A.
soft

B.
strong

C.
forced

D.
lazy

E.
delayed

Explanation:
From the man pages:
umount – unmount file systems
-l Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all
references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)