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.