Final answer:
The correct answer to which of the listed options is not an operating system is c. Microsoft Word, as it is a word-processing application, not an operating system like Linux, Microsoft Vista, or Mac OS X.
Step-by-step explanation:
The question asks which among the given options is NOT an operating system. An operating system (OS) is a system software that manages computer hardware, software resources, and provides common services for computer programs. Microsoft Word is not an operating system, while Linux, Microsoft Vista, and Mac OS X are examples of operating systems. Out of the choices provided:
- Linux is a family of open-source Unix-like operating systems based on the Linux kernel.
- Microsoft Vista is a version of the Windows operating system developed by Microsoft.
- Microsoft Word is not an operating system, it is a word-processing application that is part of the Microsoft Office suite.
- Mac OS X is an operating system developed by Apple Inc. for Mac computers.
Therefore, the correct answer is c. Microsoft Word, which is NOT an operating system.