Concept:DOS is an acronym for a well-known family of operating systems that work from disk storage.
Explanation:The full form of DOS is Disk Operating System.
It is an operating system that runs directly from a hard-disk drive.
The most common versions are Microsoft's MS-DOS and IBM PC DOS, both introduced in 1981.
Other compatible versions include DR DOS, ROM DOS, and FreeDOS.
Later versions of Windows made DOS unnecessary for most users.
Therefore, among the given options, only Disk Operating System correctly expands the acronym DOS.
Answer:C. Disk Operating System