The Company core switches use 802.1Q trunks to connect to each other.  How does 802.1Q  trunking keep track of multiple VLANs？ （）

• A、 It tags the data frame with VLAN information and recalculates the CRC value
• B、 It encapsulates the data frame with a new header and frame check sequence
• C、 It modifies the port index of a data frame to indicate the VLAN
• D、 It adds a new header containing the VLAN ID to the data frame
• E、 None of the other alternatives apply