Which statement is true about Session Border Controller architectures and realm bridging?

A: The Hosted NAT Traversal (HNT) architecture focuses on the border point between two different service provider networks, both in the home realm. B: The Hosted IP architecture focuses on the border point between one enterprise network realm and one service provider network realm. C: The Access-backbone architecture focuses on the border point between two backbone realms. D: The Peering architecture focuses on the border point between two different service provider networks and their realms. E: The Gateway architecture Focuses on the border point between one enterprise network realm and one service provider network realm.