Final answer:
Expansion cards enhance a computer's capabilities, such as a graphics card for visuals, a network interface card for networking, a USB card for additional USB ports, and a sound card for improved audio.
Step-by-step explanation:
The scenario in which different expansion cards can be used correlates directly with their functions. For example, a graphics card (A) is essential for rendering images and is commonly used for gaming, video editing, and graphic design to provide high-quality visuals on a monitor.
A network interface card (B), also known as a networking card, allows a computer to communicate over a network, such as connecting to the internet or a local area network (LAN). On the other hand, a USB card (C) provides additional USB ports which could be useful for connecting multiple USB devices, such as a memory card reader as described in the reference. Finally, a sound card (D) enhances the audio capabilities of a computer, which is particularly useful for professionals in music production or for a higher fidelity sound experience.