In frame-mode MPLS, which statement is true?

A.
MPLS inserts a 32-bit label after the Layer 3 header.

B.
MPLS replaces the Layer 2 header with a 32-bit label.

C.
MPLS replaces the Layer3 header with a 32-bit label.

D.
MPLS inserts 32-bit label between the Layer 2 and Layer 3 headers.