What is one of the functions of a LISP ingress tunnel router?

What is one of the functions of a LISP ingress tunnel router?
A . Ability to integrity-check LISP site registration messages using a SHA2-based HMAC algorithm
B . Responsible for finding EID-to-RLOC mappings for all traffic destined for LISP-capable sites
C . Accept encapsulation Map-request messages, decapsulate them to the MS responsible for the ETR authoritative for the requested EIDs
D . Allows EIDs and RLOCs to communicate in a LISP site that contains EIDs in one address family and RLOCs in a different address family

Answer: B