After replacing the NIC card of a PC on the LAN, your Cisco switch shows a new MAC address is attached to that port. Which of the following answer choices below correctly describe a MAC address?（）

• A、It is a globally unique IP address.
• B、It is a globally unique 48 bit address
• C、It is provided by the manufacturer of the NIC.
• D、It is used as part of the IPX/SPX configuration.
• E、It is a logical address.