Which file system is primarily used by Unix-based operating systems?

Unix-based operating systems predominantly utilize the UFS, or Unix File System, which is designed specifically for these environments. UFS supports a range of features conducive to the requirements of Unix systems, such as file hierarchies, access rights, and performance efficiency in managing storage.

UFS is built to handle the demands of multi-user environments, providing robust support for features like file permissions and links that are essential in Unix derivatives. This file system also ensures a high level of data integrity and reliability, which is crucial for system stability.

In contrast, NTFS (New Technology File System) is primarily used by Windows operating systems and is not compatible with Unix. FAT (File Allocation Table) is an older file system type that is less commonly used in modern server environments and lacks many of the advanced features of UFS. VMFS (Virtual Machine File System) is specifically designed for VMware environments to manage virtual machines and is not used broadly across Unix systems. Thus, the correct answer reflects the dedicated nature of UFS for Unix-based operating systems.