Answer :
An operating system performs all the activities in the given options except D: allowing a user to do word processing.
An operating system (OS) is a system program that, after being initially loaded into the computer system by a boot program, manages and handles all of the other application programs in a computer. The application programs make use of the operating system by creating requests for services through a defined API or application program interface. Simply, an operating system is responsible to manage computer hardware, and software resources, as well as providing common services for computer programs.
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