Windows is NOT correct.
Key Points
- Among the options, only Windows is NOT an open-source operating system.
- Windows is a closed source operating system marketed by Microsoft.
- Microsoft first introduced the Windows operating system on 20 November 1985.
- Closed Operating Systems are built with numerous codes and complex programming and that is called source code.
- An Open-source Operating System is the Operating System in which source code is visible publically and editable.
- The operating system is a collection of programs that controls the overall operations of the computer.
- Operating system is a System software in computers.
- It works as an interface between user and computer hardware components.
- Examples of operating systems are:
- Linux.
- Unix.
- DOS.
- Windows.
- Ubuntu.
- Embedded operating system.
- OpenBSD.
- Mac OS.


