In operating systems, what is the most accurate definition of a ‘‘process’’ in contrast to a program stored on disk or a job in secondary memory?

Introduction / Context:
Understanding the precise meaning of a process is foundational in operating systems. While “program,” “job,” and “file” are related terms, a process uniquely denotes the active, running instance with resources and execution context managed by the OS. This distinction underpins scheduling, synchronization, and resource allocation.

Given Data / Assumptions:

• A program can be stored on disk in a high-level language or as an executable image.
• A process includes runtime state such as registers, stack, heap, and open handles.
• The OS tracks processes via process control blocks (PCBs).

Concept / Approach:
A process is not merely code; it is code in motion. When the loader creates an address space and the scheduler dispatches it on a CPU, the program becomes a process with its own program counter, stack, heap, and I/O context. Therefore, the most accurate definition is “a program in execution.”

Step-by-Step Solution:

Verification / Alternative check:
OS textbooks and utilities (for example, TASKLIST, ps) enumerate processes, not programs; they show runtime instances with PIDs and states (running, ready, blocked).

Why Other Options Are Wrong:

• Contents of main memory: Too broad; memory holds many things beyond a single process.
• Program in a high-level language kept on disk: That is a static program, not executing.
• A job in secondary memory: Jobs may be queued; not necessarily executing.
• None of the above: Incorrect because “a program in execution” is correct.

Common Pitfalls:
Equating files with running instances, or assuming a process is only the code segment without considering its dynamic state and OS-managed resources.

Final Answer:
A program in execution