In which of the following scenarios is the Operating System primarily involved?

The chosen answer, managing computer hardware operations, is correct because the primary role of an operating system (OS) is to serve as an intermediary between users and the computer hardware. The operating system is responsible for managing and coordinating the use of hardware resources such as the CPU, memory, storage devices, and input/output devices. It handles tasks like memory allocation, process scheduling, and device management, ensuring that applications can effectively communicate with the hardware components to perform their functions.

In the context of the other scenarios, while they may involve the OS indirectly, they are not the primary responsibilities of the operating system. For instance, developing new software applications primarily engages developers coding and designing the software, while network connections pertain to networking protocols and configurations that might involve middleware or network stacks rather than direct OS functions. Building user interfaces focuses on the graphical layout and interactions of software applications which is handled at the application layer rather than by the operating system itself. Thus, the selected answer clearly identifies a scenario where the operating system plays a critical and direct role.