In a computer system, what are the main components, and how do hardware, operating system, application programs and users relate to each other?

Introduction / Context:
When studying operating systems, it is helpful to view the entire computer system as a set of layers or components. Most textbooks describe four main components: the hardware, the operating system, the application programs and the users. Understanding this structure clarifies the role of the operating system as a resource manager and as an interface between users, applications and hardware.

Given Data / Assumptions:

• The computer system contains physical devices such as CPU, memory and I/O devices.

• There is system software that manages resources and provides services.

• There are application programs that solve user problems.

• Human users or other systems interact with the applications and the operating system.

Concept / Approach:
The hardware is the lowest level component and executes machine instructions. The operating system sits on top of the hardware and manages it, providing services such as process management, memory management and device control. Application programs use the operating system interface to perform useful work, such as text editing or web browsing. Users interact with the application programs or sometimes directly with the operating system through commands. The correct option must mention all four components and describe the operating system as a mediator.

Step-by-Step Solution:
Step 1: Identify hardware as the physical part of the system: CPU, memory, disks, keyboard, display and so on. Step 2: Recognize the operating system as system software that controls hardware and provides a platform for applications. Step 3: Identify application programs as software that directly solves user tasks, such as word processors, browsers or games. Step 4: Understand that users are the people or external systems that actually use applications and, indirectly, the hardware through the operating system. Step 5: Select the option that lists hardware, operating system, application programs and users, and states their relationship correctly.

Verification / Alternative check:
You can verify by drawing the usual diagram: hardware at the bottom, operating system above it, application programs above the operating system and users at the top. Every request from a user flows down through applications and the operating system to the hardware and results flow back up. This model is standard in operating system texts and clearly matches the chosen option.

Why Other Options Are Wrong:
Option B is wrong because it ignores software and treats it as not a component, which contradicts the layered view used in computing. Option C is wrong because network cables and the internet are just parts of a broader hardware and network environment and do not represent the full set of components. Option D is wrong because printers and scanners are only specific I/O devices and not the complete computer system by themselves.

Common Pitfalls:
Students sometimes focus solely on hardware and forget that software is equally essential. Another pitfall is to overlook the role of the operating system as an intermediary and to think that applications directly manage hardware. Recognizing that each layer provides an abstraction for the layer above improves understanding of why operating systems exist and what problems they solve.

Final Answer:
Thus, the main components of a computer system are hardware, operating system, application programs and users, with the operating system acting as an interface between hardware and the applications used by people.