Explanation:

The operating system (OS) is the master control program that manages all the computer's hardware and software resources. It acts as an intermediary between the user and the computer hardware, providing a platform for application programs to run. The OS is responsible for managing the CPU, memory, storage devices, and input/output operations, effectively telling the computer how to utilize its various components. Option (a) 'utility' software performs specific maintenance tasks, but doesn't manage the entire system. Option (b) 'application' software performs user-specific tasks (e.g., word processing) and relies on the OS. Option (d) 'network' refers to interconnected computers, not the core software managing a single computer's components. Therefore, (c) 'operating system' is the correct answer.