What is one primary role of an operating system (OS)?

One primary role of an operating system (OS) is to control user interaction with hardware. The OS acts as an intermediary between the user and the computer hardware, allowing users to execute commands, run applications, and manage files through a user-friendly interface. This involves handling input from devices like keyboards and mice and directing output to displays and printers.

By managing how users interact with the hardware components, the OS ensures that different programs can operate without conflict over resources such as memory and processing power. This encompasses everything from the graphical user interface (GUI) that allows users to navigate and control the system, to command-line interfaces for more advanced users.

The other options, while relevant to some aspects of computing, do not encompass the primary responsibilities of an OS. Direct hardware access is typically managed on behalf of applications through the OS, rather than allowing direct access to the user. System notifications can be generated as part of an OS's functionality, but they are a secondary feature rather than a primary role. Managing the application development lifecycle is not a direct function of the OS, but rather a task typically handled by development frameworks and tools that run on top of an OS.