Which of the following is NOT an operating system?

Correct option is C

The correct answer is: (c) Microsoft Access

Explanation:

• Linux, Unix, and DOS are all operating systems, which manage hardware and software resources on a computer.
• Microsoft Access is not an operating system; it is a database management system (DBMS) used for creating, managing, and manipulating databases.

Thus, Microsoft Access is the correct option as it is not an operating system.