Which is a correct statement about MAC addresses?

A. Organizationally unique identifiers (OUIs) create a unique MAC address.
B. The first 24 bits of a MAC address is specified by the vendor.
C. The IEEE is responsible for MAC address uniqueness.
D. If the I/G bit is set to 1, then the frame identifies a broadcast or multicast.

D. When the Individual/Group (I/G) high order bit is set to 1, the frame is a broadcast or a multicast transmission. The OUI assigned by the IEEE is only partially responsible for MAC uniqueness. The vendor is responsible for the last 24 bits of a MAC address.