Which of the following Linux file systems not only supports journaling but also modifies important data structures of the file system, such as the ones destined to store the file data for better perfo

GRUB (Grand Unified Bootloader) is a boot loader program used to load the operating system kernel, not a file system.

LILO (Linux Loader) is a legacy Linux boot loader responsible for initializing the OS at startup, not a file system with journaling or data structure features.

Ext4 (Fourth Extended Filesystem) supports journaling to ensure file system consistency after crashes, and it also introduces the extent-based storage model, which replaces the indirect block mapping of Ext3. Extents are contiguous blocks of storage that reduce fragmentation and improve performance for large files. These structural modifications to how file data is stored distinguish Ext4 from a simple journaling-only file system.

FAT32 (File Allocation Table 32) is a legacy file system that uses a flat allocation table structure and does not support journaling or extent-based data structures.