Which statement best describes an Operating System (OS)?

• A. A browser
• B. A data backup tool
• C. A type of network switch
• D. Software of a computer system that is responsible for the management and coordination of all activities and the sharing of computer resources

Answer: (D)

The operating system is the software layer between applications and hardware that manages and coordinates everything the computer does and how its resources are shared. It decides which programs run, allocates memory, handles input/output devices, and provides services needed by applications, all while enforcing security and access controls. This broad coordinating role—managing processes, memory, files, devices, and user permissions—is what makes the description of the OS as software responsible for the management and coordination of all activities and the sharing of computer resources the best fit. A browser, a data backup tool, and a network switch don’t capture this overarching stewardship: the browser and backup tool are individual applications, and the switch is hardware.