Which two statements about cell-mode MPLS loop prevention mechanisms are true?

Which two statements about cell-mode MPLS loop prevention mechanisms are true? (Choose two)

A.
MPLS relies on the loop prevention mechanism MP-BGPB.
Loop detection algorithms in LDP ensure that loops are not present.

B.
MPLS relies on the loop prevention mechanisms embedded in the IGP.

C.
MPLS labels contain a Time-To-Live (TTL) field that prevents packets from looping indefinitely.

Explanation:

Not A: A is not correct too since running cell mode MPLS doesn’t require neither MPLS VPN nor MP-iBGP.
Not C: C is not correct as ATM switches cannot run IGP.