The correct answer is B. MAC address.
A MAC address (Media Access Control address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used in the Media Access Control sublayer of the Data Link Layer of the Open Systems Interconnection (OSI) model.
An IP address (Internet Protocol address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.
A NIC (network interface card) is a computer hardware component that connects a computer to a computer network. Most commonly, a NIC is a small circuit board that plugs into a computer’s motherboard. NICs provide physical access to a network, and provide a way for the computer to communicate with other devices on the network.
An organizationally unique identifier (OUI) is a unique identifier assigned by the Institute of Electrical and Electronics Engineers (IEEE) to identify the manufacturer of a network interface controller (NIC). The OUI is the first three bytes of a MAC address.