Final answer:
The UNIX operating system supports multiple file systems, with UFS being one of the most commonly used file systems.
Step-by-step explanation:
The UNIX operating system supports multiple file systems, but one of the most commonly used file systems is the UFS (UNIX File System). UFS is a file system native to UNIX-based operating systems and is designed to provide efficient storage and access to files. It supports features such as file permissions, symbolic links, and file metadata.