Which of the following commands will allow an administrator to adjust the number of mounts after which an existing filesystem will be checked by e2fsck?

debugfs is an interactive filesystem debugger used for low-level inspection and repair, not for adjusting mount-count thresholds.

dumpe2fs displays filesystem superblock and block group information in read-only mode; it cannot modify filesystem parameters.

mode2fs is not a valid Linux command; no standard utility by that name exists for ext filesystem management.

tune2fs with the '-c' option sets the maximum number of mounts before the filesystem is automatically checked by e2fsck on the next boot. For example, 'tune2fs -c 20 /dev/sda1' causes a check after every 20 mounts. This is a post-creation tuning operation applied to an existing ext filesystem.

mke2fs creates a new ext filesystem on a device and cannot adjust parameters on an already existing filesystem.