What is the purpose of a MAC address?

The purpose of a MAC (Media Access Control) address is to uniquely identify a network card or network interface controller (NIC) on a local network. Every device connected to a network, whether it's a computer, printer, or smartphone, has a unique MAC address assigned to it, which is used to differentiate between devices within the same local area network (LAN).

This unique identifier is critical in network communication because it helps ensure that the data packets being sent across the network reach the correct device. While other options mention addresses for data packets or security measures, they do not capture the primary role of a MAC address, which is to serve as a hardware identifier for network devices. The MAC address operates at the data link layer of the OSI model and is essential for local network operations, such as routing and switching of data.

The focus on the unique identification aspect is what makes this answer correct, as it reflects the fundamental role of a MAC address in networking.