When running basic MPLS in conjunction with VPNs, how many labels does each packet contain?

A.
Each packet contains one label that identifies the VPN.

B.
Each packet contains at least two labels. One label identifies the path to the egress router and
one that
identifies the VPN.

C.
Each packet contains at least three labels. One label identifies the ingress router, one identifies
the egress router and one identifies the path that will be taken.

D.
Each packet contains at least three labels. One label identifies the ingress router, one label
identifies the path to the egress router, and one identifies the VPN.