What is file system journaling?

A.
a feature implemented in some file system drivers that provides a snapshot journal entry of a file system’s entire state

B.
a logging facility, implemented by the fsjournald daemon, that records all file system configuration changes to /var/log/filesystems

C.
a feature of some file system drivers that makes file system operations atomic across reboots

D.
a feature of some file system drivers that makes all disk I/O operations atomic