Which of the following best describes the operating system's core responsibilities?

• A. Running applications directly without OS.
• B. Handling only printing tasks.
• C. Allocating CPU time, managing memory, and offering a user interface.
• D. Storing all files on disk.

Answer: (C)

An operating system’s main job is to manage the computer’s resources and provide a usable interface for people and programs. Allocating CPU time is essential because it decides which tasks run when, enabling multitasking and responsiveness. Memory management handles how program data is stored in fast memory, prevents interference between programs, and allows larger applications to run smoothly through techniques like virtual memory. The user interface—whether graphical or command-line—lets you start programs, manage files, and control the system. Taken together, these functions capture the OS’s core responsibilities: coordinating hardware resources and offering a stable, accessible environment for software.

The other options miss the broader role: running applications directly without an OS ignores the need for coordinated resource management and services; handling only printing tasks is far too narrow; storing all files on disk describes storage duties rather than the full set of essential operating system responsibilities.