Where is the MPLS label imposed?
A.
after the Layer 3 header and before the Layer 2 payload
B.
after the Layer 3 header and before the Layer 4 payload
C.
after the Layer 2 header and before the Layer 1 payload
D.
after the Layer 1 header and before the Layer 2 payload
E.
after the Layer 2 header and before the Layer 3 payload