The correct answer is D. All of the above.
The operating system is a software program that manages the computer’s hardware and software resources and provides a platform for other programs to run. It is responsible for tasks such as scheduling tasks, managing memory, and controlling input/output devices.
The operating system manages memory by allocating memory to different programs and processes. It also ensures that no program uses more memory than it is allowed to.
The operating system manages the processor by scheduling tasks for the processor to execute. It also ensures that no program monopolizes the processor.
The operating system manages disk and I/O devices by providing a way for programs to access these devices. It also manages the file system, which is used to store data on the disk.
In addition to the tasks listed above, the operating system also performs many other tasks, such as managing security, providing a user interface, and running background services.