Which statement best describes the role of an operating system in process management and context switching?

• A. It schedules processes and threads, allocates CPU time, and saves/restores the processor state during context switches.
• B. It only handles file input/output operations.
• C. It manages user authentication and access control.
• D. It compiles programs into machine code.

Answer: (A)

The main idea is how an operating system manages multiple tasks and switches between them. The OS is responsible for scheduling processes and threads, deciding which task gets CPU time next, and allocating that time fairly or efficiently. When a switch occurs, the OS saves the current task’s processor state—things like the program counter, CPU registers, and stack pointer—so it can later resume exactly where it left off, and then loads the state of the next task to run. This saving and restoring of state during context switches is what makes multitasking possible.

Other options miss the focus on how tasks are managed and swapped. File I/O handling is about input/output operations, security and access control cover protection policies, and compiling is about turning code into executable machine instructions. None of these center on the ongoing management of active tasks and the mechanics of switching between them.