Which of the following file systems is used by both CD and DVD?

Network File System (NFS) is a network-based remote file access protocol and has no relevance to optical disc file systems.

New Technology File System (NTFS) is a Windows disk file system for hard drives and SSDs, not designed for or used on optical media like CDs or DVDs.

Compact Disk File System (CDFS), also known as ISO 9660, is a read-only file system specific to CDs and is not the standard used by DVDs.

Universal Disk Format (UDF) was developed by the Optical Storage Technology Association (OSTA) and is the file system used across both CD and DVD formats, as well as Blu-ray. It supports read/write operations, large file sizes, and is the standard required for DVD-Video and DVD-ROM, making it the format that spans both optical media types.