The correct answer is C. fsck.
fsck is a command-line utility for checking and repairing Linux file systems. It can be used to check for errors in the file system, and to repair any errors that are found. fsck is typically run after a system crash or power outage, as these events can sometimes cause file system corruption.
mkfs is a command-line utility for creating file systems. It can be used to create new file systems, or to reformat existing file systems. mkfs is typically used when creating a new partition, or when formatting a partition that has been damaged.
fdisk is a command-line utility for partitioning disks. It can be used to create, delete, and resize partitions. fdisk is typically used when creating a new partition table, or when resizing an existing partition.
mount is a command-line utility for mounting file systems. It can be used to mount a file system on a directory, or to unmount a file system. mount is typically used when you want to access files on a partition that is not currently mounted.
None of the above is not the correct answer.