What is the function of an Operating System?

An operating system serves multiple essential functions that are critical for the overall operation of a computer or device. One primary role is to run applications by managing the execution of various programs and ensuring they have the necessary resources.

Additionally, an operating system manages system resources, which includes hardware components like the CPU, memory, storage devices, and input/output peripherals. This management ensures that these resources are allocated efficiently among competing tasks, thereby optimizing performance and maintaining system stability.

Furthermore, operating systems facilitate user interaction, providing a user interface that allows users to communicate with the computer effectively. This interface can be graphical (GUI) or command-line based, offering users the means to execute commands, run applications, and manage files intuitively.

Given that an operating system encompasses these three vital capabilities—running applications, managing system resources, and facilitating user interaction—the correct response encompasses all of these aspects, making "all of the above" the comprehensive answer.