Which of the following is NOT a function of an Operating System?

An operating system serves several key functions that are crucial for the management of computer hardware and software resources. One of its important roles is managing memory allocation, where it tracks and allocates memory space to different processes as needed. It also handles input and output operations, coordinating interactions between the user and the computer's hardware, such as keyboards, mice, and printers. Furthermore, operating systems play a vital role in ensuring data security and access rights, providing mechanisms to control user permissions and protect data from unauthorized access.

Creating graphical user interfaces (GUIs) is a more specific task that pertains to user interface design, which can be influenced by the operating system; however, it is not a core function that all operating systems perform universally for all applications. Some applications may come with their own GUI frameworks or libraries that do not rely entirely on the operating system’s default graphical interface capabilities. Therefore, while many operating systems provide tools or environments for developers to create GUIs, they do not create graphical user interfaces for all applications as a fundamental responsibility. This distinguishes it from the other listed functions, which are intrinsic duties of an operating system.