Which of the following is not an application software

Application software is any program written to help a user perform a specific task, such as typing documents, drawing graphics, or preparing presentations. Application software runs on top of and depends on another category of software called system software, which manages the computer's hardware and provides the platform on which applications run.

Word processors and drawing tools are clear examples of application software: one lets a user create and edit documents, and the other lets a user create and edit graphics and illustrations. A word-processing program designed for early Apple computers also falls into this same category, since it exists purely to let users type and format text. An operating system, however, is fundamentally different in purpose. It is system software: it manages the computer's memory, processes, files, and hardware devices, and it must be running before any application software can be opened at all. Because it manages the machine itself rather than performing a specific end-user task, it does not belong in the application software group.

A useful test when classifying software is to ask whether the program manages the computer itself (system software) or whether it helps a person accomplish a task using the computer (application software).