Which one of the following is not an operating system?

Which one of the following is not an operating system?

MS-Windows
Linux
Ubuntu
MS-Excel
This question was previously asked in
UPSC CAPF – 2022
An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs. MS-Windows, Linux, and Ubuntu are all examples of widely used operating systems. MS-Excel, on the other hand, is an application software, specifically a spreadsheet program, used for data analysis, calculations, and visualization. It runs *on* an operating system.
The question asks to identify which option is *not* an operating system. Operating systems are fundamental software that allows other programs to run and manage hardware, while application software performs specific user tasks.
Examples of operating systems include Microsoft Windows, macOS, Linux, Android, and iOS. Examples of application software include word processors (like MS Word), web browsers (like Chrome, Firefox), email clients, media players, games, and spreadsheet programs (like MS-Excel).