Regarding the MPLS processing mode for TTL, which of the following descriptions is correct?

Regarding the MPLS processing mode for TTL, which of the following descriptions is correct?
A . In Pipe mode, when an IP packet passes through an MPLS network, at the ingress point, the IP TTL minus 1 is mapped to the MPLS TTL field
B . The TTL in the MPLS label has the same meaning as the TTL field in the IP header. TTL prevents routing loops in MPLS networks
C . In Unifor mode, when IP packets pass through the MPLS network, the IP TTL of the ingress point is decremented by 1. MPLS TTL field is a fixed value
D . In MPLS VPI, if you need to hide the structure of the MPLS backbone network, you can use the Uniform mode on the Ingress for private network packets.

Answer: B