Which two of these are characteristics of the 802.1 Q protocol? (Choose two.)

A.
it modifies the 802.3 frame header, and thus requires that the FCS be recomputed.

B.
It is used exclusively for tagging VLAN frames and does not address network reconvergence following switched network topology changes.

C.
it is a Layer 2 messaging protocol which maintains VLAN configurations across networks.

D.
it is a trunking protocol capable of carrying untagged frames.

E.
It includes an 8-bit field which specifies the priority of a frame.

Explanation:
802.1 Q protocol, or Virtual Bridged Local Area Networks protocol, mainly stipulates the realization of the VLAN. 802.1 Q is a standardized relay method that inserts 4 bytes field into the original Ethernet frame and re-calculate the FCS. 802.1 Q frame relay supports two types of frame: marked and non-marked. Non-marked frame carries no VLAN identification information.