In personal computer hardware, which option lists only basic expansion card types that can be installed into motherboard slots to add new functionality?

Introduction / Context:
Desktop personal computers are designed to be expandable. Motherboards typically provide expansion slots such as PCI, PCI Express, or older standards that allow you to install additional cards. These expansion cards add or enhance capabilities like graphics, audio, networking, or communication. This question asks you to identify which group of components consists entirely of typical expansion card types rather than core components or external peripherals.

Given Data / Assumptions:

• The focus is on internal expansion cards that plug into motherboard slots.
• Common examples are video cards, sound cards, network interface cards, and modem cards.
• Some listed items are core system components such as the CPU and power supply.
• Other listed items are external peripherals or storage devices, not expansion cards.

Concept / Approach:
An expansion card is a printed circuit board that fits into an expansion slot on the motherboard and provides extra functions beyond what the motherboard offers by default. Graphics or video cards handle video output, sound cards manage audio processing, network interface cards provide wired or wireless networking, and modem cards handle telephone line communication. These cards typically have metal brackets with ports exposed at the back of the computer. Core components such as the CPU, RAM modules, and power supply are part of the base system, while peripherals like keyboard, mouse, and printer connect externally.

Step-by-Step Solution:
Step 1: Identify which items in each option are commonly sold as internal expansion cards.Step 2: Recognize that video cards, sound cards, network interface cards, and modem cards are classic examples of PCI or PCI Express expansion cards.Step 3: Note that CPUs, RAM modules, heat sinks, and power supplies are essential system components, not expansion cards, even though they are installed inside the case.Step 4: Observe that keyboards, mice, monitors, and printers are external peripherals that connect via ports or wireless links, not via expansion slots.Step 5: See that drives such as hard disks and optical drives are storage devices that connect via SATA or similar interfaces, not via expansion card slots.

Verification / Alternative check:
To verify, think about assembling or upgrading a desktop system. When you want to improve gaming performance, you install a new graphics card in a PCI Express x16 slot. To add better audio, you may install a dedicated sound card. To connect to a wired network, you can install a network interface card if the motherboard does not already include one. Each of these is a clear example of an expansion card. By contrast, replacing the CPU or power supply involves different sockets and mounting methods, and connecting a keyboard or printer uses USB or similar ports.

Why Other Options Are Wrong:
Option B is incorrect because the CPU, RAM module, heat sink, and power supply are not considered expansion cards; they are fundamental system components. Option C is wrong because keyboard, mouse, monitor, and printer are external peripherals, not cards. Option D is incorrect because hard drives, solid state drives, and optical drives are storage devices that use drive bays and cables, not motherboard expansion slots.

Common Pitfalls:
A common mistake is to assume that anything inside the computer case is an expansion card. In reality, only boards that plug into expansion slots qualify. Another pitfall is to confuse external USB dongles with internal cards; while they provide similar functions, their form factor and connection method are different. Understanding the physical layout of a PC and the role of expansion slots makes these distinctions clear.

Final Answer:
The group that lists only typical expansion card types is video card, sound card, network interface card, and modem card, which is option A.