Final answer:
The expansion card for network and Internet connections on the motherboard is a Network card. It is designed to enable network communications for the computer, differing from other cards like graphics, sound, or USB cards that serve other purposes.
Step-by-step explanation:
The expansion card referenced in the question is used for network connections, which is an integral part of a computer system that allows it to connect to the internet or other networks. The correct answer to this question is c) Network card. Expansion cards, like graphics cards, sound cards, and USB cards, serve different specific purposes, for instance, graphics cards for rendering images, sound cards for audio processing, and USB cards for providing additional USB ports. In this case, the network card (also known as a network interface card, or NIC) is designed to enable a computer to communicate over a network, including connecting to the internet. It is installed onto the motherboard of the computer and typically provides an Ethernet port for a wired connection, although some may also provide wireless connectivity. When comparing to a digital camera, the principle is somewhat similar as a memory card reader functions as an interface between the memory card and a computer, utilizing USB to make the connection which allows file transfer. However, it is important to distinguish that the network card specifically relates to network connections.