Which Two Functionalities Does Cisco Expressway Provide in the Cisco

Which two functionalities does Cisco Expressway provide in the Cisco Collaboration architecture? (Choose two.)

A) Survivable Remote Site Telephony functionality
B) customer interaction management services
C) secure firewall and NAT traversal for mobile or remote Cisco Jabber and TelePresence Video endpoints
D) MGCP gateway registration
E) Secure business-to-business communications