In which portion of the frame is the 802.1q header found?

In which portion of the frame is the 802.1q header found?
A . within the Ethernet header
B . within the Ethernet payload
C . within the Ethernet FCS
D . within the Ethernet source MAC address

Answer: A

Explanation:

Frame format

Insertion of 802.1Q tag in an Ethernet frame 802.1Q does not encapsulate the original frame. Instead, for Ethernet frames, it adds a 32-bit field between the source MAC address and the EtherType/length fields of the original frame

Reference: http://en.wikipedia.org/wiki/IEEE_802.1Q