How does IEEE 802.1Q tag frames?

A. 802.1Q adds a 32-bit header to the frame with the VLAN tagging information.
B. 802.1Q adds a 32-bit header to the packet with the VLAN tagging information.
C. 802.1Q inserts a 32-bit field between the source MAC address and the type field.
D. 802.1Q inserts a 32-bit field between the destination MAC address and the type field.

C. 802.1Q inserts a field containing the 16-bit Tag Protocol ID of 0x8100, a 3-bit COS field, a 1-bit drop-eligible indicator (used with COS), and the 12=bit VLAN ID, which equals 32 bits, or 4 bytes.